Climate change in the United States

U.S. temperature record from 1950 to 2009 according to the National Oceanic and Atmospheric Administration (NOAA)

Because of global warming, there has been concern in the United States and internationally, that the country should reduce total greenhouse gas which is relatively high per capita.

In 2012, the United States experienced its warmest year on record. As of 2012, the thirteen warmest years for the entire planet have all occurred since 1998, transcending those from 1880.

From 1950 to 2009, the American government's surface temperature record shows an increase by 1 °F (0.56 °C), approximately. Global warming has caused many changes in the U.S. According to a 2009 statement by the National Oceanic and Atmospheric Administration (NOAA), trends include lake and river ice melting earlier in the spring, plants blooming earlier, multiple animal species shifting their habitat ranges northward, and reductions in the size of glaciers.

Predicting future climate changes are fraught with difficultly. Some research has warned against possible problems due to American climate changes such as the spread of invasive species and possibilities of floods as well as droughts. Changes in climate in the regions of the United States appear significant. Drought conditions appear to be worsening in the southwest while improving in the northeast for example.

President Barack Obama committed in the December 2009 Copenhagen Climate Change Summit to reduce carbon dioxide emissions in the range of 17% below 2005 levels by 2020, 42% below 2005 levels by 2030, and 83% below 2005 levels by 2050. In an address towards the U.S. Congress in June 2013, Obama detailed a specific action plan to achieve the 17% carbon emissions cut from 2005 by 2020. He included such measures as shifting from coal-based power generation to solar and natural gas production.

In 2015, according to The New York Times and others, oil companies knew that burning oil and gas could cause global warming since the 1970s but, nonetheless, funded deniers for years.

Greenhouse gas emissions by the United States

Per capita anthropogenic greenhouse gas emissions by country for the year 2000 including land-use change, per the World Resources Institute

Main article: Greenhouse gas emissions by the United States

Further information: United States federal register of greenhouse gas emissions

The United States was the second top emitter in terms of CO2 from fossil fuels in 2009. It produced 5,420 million metric tons (abbreviated as mt) of the substance, constituting 17.8% of the world's total at the time. The nation was also the second highest emitter in terms of all greenhouse gas emissions, including construction and deforestation-related changes, in 2005. Specifically, the U.S. produced 6,930 mt (15.7% of the world's total). In the cumulative emissions between 1850 and 2007, the U.S. was at the top in terms of all world nations, involved with 28.8% of the world's total.

China's emissions have outpaced the U.S. in CO2 from 2006 onward. The U.S. produced 5.8 billion metric tons of CO2 in 2006, compared to the 6.23 billion coming from China. Per capita emission figures of China are about one quarter of those of the U.S. population.

The single largest source of greenhouse gas emissions in the U.S. is power generation. For example, data from 2012 put that share as 32% of the total compared to the 28% of emissions related to transportation, 20% from industry, and 20% from other sources.

According to data from the US Energy Information Administration the top emitters by fossil fuels CO2 in 2009 were: China: 7,710 million tonnes (mt) (25.4%), US: 5,420 mt (17.8%), India: 5.3%, Russia: 5.2% and Japan: 3.6%.

In the cumulative emissions between 1850 and 2007 the top emitters were: 1. US 28.8%, 2. China: 9.0%, 3. Russia: 8.0%, 4. Germany 6.9%, 5. UK 5.8%, 6. Japan: 3.9%, 7. France: 2.8%, 8. India 2.4%, 9. Canada: 2.2% and 10. Ukraine 2.2%.

In terms of trends, carbon dioxide emissions were around 5,000 mt in 1990 and gradually increased to around 6,000 mt, with a peak occurring in 2008. The subsequent decline went on such that 2012 saw about 5,400 mt emitted.

Current and potential effects of climate change in the United States

This graph shows the decrease in snow cover in the northern hemisphere associated with climate changes from 1966 to 2008.

A January 2013 'National Climate Assessment' study on the Great Lakes region, lead by University of Michigan scholars, stated that climate change would have mixed but net-negative effects in the region by 2050. Specifically, longer growing seasons as well as higher carbon dioxide levels were predicted to increase crop yield but heat waves, droughts, and floods were also forecast to rise. The report predicted declines in ice cover on the Great Lakes that would lengthen commercial shipping season although the regions would also suffer from invasive species as well as damaging algae blooms. The negative scenario described in the study used modeling with a 3.8 to 4.9 F° range for 2000 to 2050 warming versus the 1 F° of historical warming for 1950 to 2000.

In terms of U.S. droughts, a study published in Geophysical Research Letters in 2006 about the U.S. reported, "Droughts have, for the most part, become shorter, less frequent, and cover a smaller portion of the country over the last century." It also stated that the "main exception is the Southwest and parts of the interior of the West" where "drought duration and severity... have increased."

The general impact of climate changes has been found in the journal Nature Climate Change to have caused increased likelihood of heat waves and extensive downpours. Concerns exist that, as stated by a National Institutes of Health (NIH) study in 2003, increasing "heat and humidity, at least partially related to anthropogenic climate change, suggest that a long-term increase in heat-related mortality could occur." However, the report found that, in general, "over the past 35 years, the U.S. populace has become systematically less affected by hot and humid weather conditions" while "mortality during heat stress events has declined despite increasingly stressful weather conditions in many urban and suburban areas." Thus, as stated in the study, "there is no simple association between increased heat wave duration or intensity and higher mortality rates" with current death rates being largely preventable, the NIH deeply urging American public health officials and physicians to inform patients about mitigating heat-related weather and climate effects on their bodies.

The question of whether events such as hurricanes, tornadoes, and other unusual storms have been altered by climate change in the U.S. is a subject of much uncertainty, as found in the aforementioned Nature Climate Change study. A fundamental problem exists in that records for those such events are of worse quality with poorer details than temperature and rainfall records. A comprehensive article in Geophysical Research Letters in 2006 found "no significant change in global net tropical cyclone activity" during past decades, a period when considerable warming of ocean water temperatures occurred. Significant regional trends exist such as a general rise of activity in the North Atlantic area besides the U.S. eastern coast.

Looking at the lack of certainty as to the causes of the 1995 to present increase in Atlantic extreme storm activity, a 2007 article in Nature used proxy records of vertical wind shear and sea surface temperature to create a long-term model. The authors found that "the average frequency of major hurricanes decreased gradually from the 1760s until the early 1990s, reaching anomalously low values during the 1970s and 1980s." As well, they also found that "hurricane activity since 1995 is not unusual compared to other periods of high hurricane activity in the record and thus appears to represent a recovery to normal hurricane activity, rather than a direct response to increasing sea surface temperature." The researches stated that future evaluations of climate change effects should focus on the magnitude of vertical wind shear for answers.

The frequency of tornadoes in the U.S. have increased, and some of said trend takes place due to climatological changes though other factors such as better detection technologies also play large roles. According to a 2003 study in Climate Research, the total tornado hazards resulting in injury, death, or economic loss "shows a steady decline since the 1980s". As well, the authors reported that tornado "deaths and injuries decreased over the past fifty years". They state that addition research must look into regional and temporal variability in the future.

According to the Stern Review, warming of 3 or 4 °C will lead to serious risks and increasing pressures for coastal protection in New York State.

Sea level rise has taken place in the U.S. for decades, going back to the 19th century. As stated in research published by the Proceedings of the National Academy of Sciences, west coast sea levels have increased by an average of 2.1 millimeters annually. In English notation, that equates to 0.083 inches per year and 0.83 inches per decade.

Crop and livestock production will be increasingly challenged. Threats to human health will increase.

This graph shows average drought conditions in the contiguous 48 states, according to the EPA, with yearly data going from 1895 to 2011. The curve is a nine-year weighted average.

The United States Environmental Protection Agency's (EPA) website provides information on climate change: EPA Climate Change. Climate change is a problem that is affecting people and the environment. Human-induced climate change has, e.g., the potential to alter the prevalence and severity of extreme weathers such as heat waves, cold waves, storms, floods and droughts. A report released in March 2012 by the Intergovernmental Panel on Climate Change (IPCC) confirmed that a strong body of evidence links global warming to an increase in heat waves, a rise in episodes of heavy rainfall and other precipitation, and more frequent coastal flooding. The U.S. had its warmest March–May on record in 2012. (See March 2012 North American heat wave)

According to the American government's Climate Change Science Program, "With continued global warming, heat waves and heavy downpours are very likely to further increase in frequency and intensity. Substantial areas of North America are likely to have more frequent droughts of greater severity. Hurricane wind speeds, rainfall intensity, and storm surge levels are likely to increase. The strongest cold season storms are likely to become more frequent, with stronger winds and more extreme wave heights."

NOAA had registered in August 2011 nine distinct extreme weather disasters, each totalling $1 billion or more in economic losses. Total losses for 2011 were evaluated as more than $35 billion before Hurricane Irene.

As shown in the adjacent image, wet and rainy conditions versus moments of drought in the U.S. have varied significantly over the past several decades. Average conditions for the 48 contiguous states flashed into extreme drought in the mid-1930s 'dust bowl' era as well as during the turn of the 20th century. In comparison, the mid-2000s decade and mid-1890s experienced only slight drought and had mitigating rainy periods. The National Drought Mitigation Center has reported that financial assistance from the government alone in the 1930s dry period may have been as high as $1 billion (in 1930s dollars) by the end of the drought.

A 2012 report in Nature Climate Change stated that there is reason to be concerned that American climate changes could increase food insecurity by reducing grain yields, with the authors noting as well that substantial other facts exist influencing food prices as such as government mandates turning food into fuel and fluctuating transport costs. The researchers concluded that U.S. corn price volatility would moderately increase with American warming with relatively modest rises in food prices assuming that market competition and integration partly mitigated climate affects. They warned that biofuels mandates would, if present, widely increase corn price sensitivity to U.S. warming.

Climate scientists have hypothesized that stratospheric polar vortexs jet stream will gradually weaken as a result of global warming and thus influence U.S. conditions. This trend could possibly cause changes in the future such as increasing frost in certain areas. The magazine Scientific American noted in December 2014 that ice cover on the Great Lakes had recently "reached its second-greatest extent on record", showing climate variability.

Policy

This graph shows U.S. energy-related CO2 emissions from 1980 to 2012 according to the EIA.

Main article: Climate change policy of the United States

The politics of global warming is played out at a state and federal level in the United States. Attempts to draw up climate change policy are being made at a state level to a greater extent than at a federal level, although the national debate has continued. President Obama committed in the 2009 Copenhagen Climate Change Summit to an American reduction in carbon dioxide emissions in the range of 17% below 2005 levels by 2020, 42% below 2005 levels by 2030, and 83% below 2005 levels by 2050.

Federal policy

See also: Executive Order 13514

The United States, although a signatory to the Kyoto Protocol, has neither ratified nor withdrawn from the protocol. In 1997, the US Senate voted unanimously under the Byrd–Hagel Resolution that it was not the sense of the senate that the United States should be a signatory to the Kyoto Protocol. In 2001, former National Security Adviser Condoleezza Rice, stated that the Protocol "is not acceptable to the Administration or Congress".

In March 2001, the Bush Administration announced that it would not implement the Kyoto Protocol, an international treaty signed in 1997 in Kyoto, Japan that would require nations to reduce their greenhouse gas emissions, claiming that ratifying the treaty would create economic setbacks in the U.S. and does not put enough pressure to limit emissions from developing nations. In February 2002, Bush announced his alternative to the Kyoto Protocol, by bringing forth a plan to reduce the intensity of greenhouse gasses by 18 percent over 10 years. The intensity of greenhouse gasses specifically is the ratio of greenhouse gas emissions and economic output, meaning that under this plan, emissions would still continue to grow, but at a slower pace. Bush stated that this plan would prevent the release of 500 million metric tons of greenhouse gases, which is about the equivalent of 70 million cars from the road. This target would achieve this goal by providing tax credits to businesses that use renewable energy sources.

Climate scientist James E. Hansen, director of NASA's Goddard Institute for Space Studies, claimed in a widely cited New York Times article in 2006 that his superiors at the agency were trying to "censor" information "going out to the public." NASA denied this, saying that it was merely requiring that scientists make a distinction between personal, and official government, views in interviews conducted as part of work done at the agency. Several scientists working at the National Oceanic and Atmospheric Administration have made similar complaints; once again, government officials said they were enforcing long-standing policies requiring government scientists to clearly identify personal opinions as such when participating in public interviews and forums.

President Barack Obama said in September 2009 that if the international community would not act swiftly to deal with climate change that "we risk consigning future generations to an irreversible catastrophe ... The security and stability of each nation and all peoples—our prosperity, our health, and our safety—are in jeopardy, and the time we have to reverse this tide is running out." President Obama said in 2010 that it was time for the United States “to aggressively accelerate” its transition from oil to alternative sources of energy and vowed to push for quick action on climate change legislation, seeking to harness the deepening anger over the oil spill in the Gulf of Mexico. The 2010 United States federal budget proposed to support clean energy development with a 10-year investment of US $15 billion per year, generated from the sale of greenhouse gas (GHG) emissions credits. Under the proposed cap-and-trade program, all GHG emissions credits would be auctioned off, generating an estimated $78.7 billion in additional revenue in FY 2012, steadily increasing to $83 billion by FY 2019.

President Obama committed in the December 2009 Copenhagen Climate Change Summit to reduce carbon dioxide emissions in the range of 17% below 2005 levels by 2020, 42% below 2005 levels by 2030, and 83% below 2005 levels by 2050. Data from an April 2013 report by the Energy Information Administration (EIA), showed a 12% reduction in the 2005 to 2012 period. Just over half of this decrease has been attributed to the recession, and the rest to a variety of factors such as replacing coal-based power generation with natural gas and increasing energy efficiency of American vehicles (according to a Council of Economic Advisors analysis).

In an address towards the U.S. Congress in June 2013, the President detailed a specific action plan to achieve the 17% carbon emissions cut from 2005 by 2020, including measures such as shifting from coal-based power generation to solar and natural gas production. Some Republican and Democratic lawmakers expressed concern at the idea of imposing new fines and regulations on the coal industry while the U.S. still tries to recover from the world economic recession, with Speaker of the House John Boehner saying that the proposed rules "will put thousands and thousands of Americans out of work". Christiana Figueres, executive director of the UN's climate secretariat, praised the plan as providing a vital benchmark that people concerned with climate change can use as a paragon both at home and abroad.

Role of the US military

The US military is an unequivocal validator of climate science, and its current efforts to value true costs and benefits of energy conservation and increased use of renewables can serve as drivers of change, according to a 2014 study from the University of Pennsylvania Legal Studies Department.

A 2014 report described the projected climate change as a “catalyst for conflict”. The DOD had issued a Fiscal Year 2012 Climate Change Adaptation Roadmap, in which it outlined its vulnerabilities, yet the Government Accountability Office (GAO) found, that installation officials rarely proposed projects with climate change adaptation, because the processes for approving and funding military construction do not include climate change adaptation in the ranking criteria for projects.

State and regional policy

Across the country, regional organizations, states, and cities are achieving real emissions reductions and gaining valuable policy experience as they take action on climate change. These actions include increasing renewable energy generation, selling agricultural carbon sequestration credits, and encouraging efficient energy use. The U.S. Climate Change Science Program is a joint program of over twenty U.S. cabinet departments and federal agencies, all working together to investigate climate change. In June 2008, a report issued by the program stated that weather would become more extreme, due to climate change. States and municipalities often function as "policy laboratories", developing initiatives that serve as models for federal action. This has been especially true with environmental regulation—most federal environmental laws have been based on state models. In addition, state actions can have a significant impact on emissions, because many individual states emit high levels of greenhouse gases. Texas, for example, emits more than France, while California's emissions exceed those of Brazil. State actions are also important because states have primary jurisdiction over many areas—such as electric generation, agriculture, and land use—that are critical to addressing climate change.

Many states are participating in Regional climate change initiatives, such as the Regional Greenhouse Gas Initiative in the northeastern United States, the Western Governors' Association (WGA) Clean and Diversified Energy Initiative, and the Southwest Climate Change Initiative.

Inside the ten northeastern states implementing the Regional Greenhouse Gas Initiative, carbon dioxide emissions per capita decreased by about 25% from 2000 and 2010, as the state economies continued to grow while enacting various energy efficiency programs.

International agreements

The US is not bound by any international agreements; it attended the Durban climate summit on 27 November 2011 with Todd Stern as the chief US. negotiator.

Cost and consequences

In 2013 there were 11 weather and climate disaster events with losses over $1 billion each in the United States. In total these 11 events losses were over $110 billion. 2013 was the warmest year ever in the contiguous United States and about one-third of all Americans experienced 10 days or more of 100-degree heat. Increasing floods, heat waves, and droughts have brought economical problems to farmers business and increased product prices.

Public response

Voluntary emissions trading

See also: Emissions trading

Also in 2003, U.S. corporations were able to trade CO₂ emission allowances on the Chicago Climate Exchange under a voluntary scheme. In August 2007, the Exchange announced a mechanism to create emission offsets for projects within the United States that cleanly destroy ozone-depleting substances.

Campus-level action

Many colleges and universities have taken steps in recent years to offset or curb their greenhouse gas emissions in relation to campus activities. On October 5, 2006, New York University announced that it plans to purchase 118 million kilowatt hours of wind power, more wind power than any college or university in the country. Later in the same month, the small campus of College of the Atlantic in Maine became the first to vow to offset all of its greenhouse gas emissions by cutting GHG emissions and investing in emissions-cutting projects elsewhere. In May 2007, the trustees of Middlebury College voted in support of a student-written proposal to reduce campus emissions as much as possible, and then offset the rest such that the campus is carbon neutral by 2016. As of November 2007, 434 campuses have institutionalized their commitment to climate neutrality by signing the American College and University Presidents Climate Commitment. On November 2-5th, 2007, thousands of young adults converged in Washington D.C. for Power Shift 2007, the first national youth summit to address the climate crisis. The Power Shift 2007 conference was a project of the Energy Action Coalition.

Political ideologies

In 2015, according to The New York Times and others, oil companies knew that burning oil and gas could cause global warming since the 1970s but, nonetheless, funded deniers for years.

Historical support for environmental protection has been relatively non-partisan. Republican Theodore Roosevelt established national parks whereas Democrat Franklin D. Roosevelt established the Soil Conservation Service. This non-partisanship began to change during the 1980s when the Reagan administration stated that environmental protection was an economic burden. Views over global warming began to seriously diverge among Democrats and Republicans when ratifying the Kyoto Protocol was being debated in 1998. Gaps in opinions among the general public are often amplified among the political elites, such as members of Congress, who tend to be more polarized.

Beyond politicians, there is a variety of views by each political party. In March 2014, Gallup found that among Democrats, 45% say they worry a great deal about the quality of the environment while the number drops to 16% for Republicans.

Political disagreement is also strongly rooted in our potential solutions to addressing climate change. Strategies such as a Cap and Trade system are still a heated argument.

Our Changing Planet

Since 1989, the U.S. Global Change Research Program has issued Our Changing Planet, an annual report summarizing "recent achievements, near term plans, and progress in implementing long term goals." The report for fiscal year 2010 was issued on October 28, 2009.

Measurement and modeling of climate systems have both improved dramatically in the last three decades, with measurements providing the hard data to calibrate the simulations, which in turn lead to improved understanding of the various systems and feedbacks and indicate areas where more and more detailed observations are needed. Recent developments in ensemble methods have improved understanding of and reduced uncertainty in hydrologic forcing by incoming radiation, particularly in areas with a complex topology. Multiple complementary model-validated proxy reconstructions indicate that recent warmth in the northern hemisphere is anomalous over at least the last 1300 years; using tree ring data, this conclusion can be extended somewhat less certainly to at least 1700 years. Improved measurement and analysis techniques have reconciled certain discrepancies between observed and projected trends in tropical surface and tropospheric temperatures: corrected buoy and satellite surface temperatures are slightly cooler and corrected satellite and radiosonde measurements of the tropical troposphere are slightly warmer.

Various forcing factors, including greenhouse gases, land cover change, volcanoes, air pollution and aerosols, and solar variability, have far ranging effects throughout the coupled ocean-atmosphere-land climate system. In the short term, impacts from ozone, black carbon, organic carbon, and sulfate on radiative forcing are predicted to nearly cancel, but long-term projections of changing emissions patterns indicate that the warming impact of black carbon will outweigh the cooling impact of sulphates. By 2100, the projected global average increase to radiative forcing is approximately 1 W/m².

Human activities influence climate and related systems through, among other mechanisms, land usage, water management, and earlier and more significant melting of snow cover due to greenhouse-effect warming. In the southwestern United States, 60% of climate-related trends in river flow, winter air temperature, and snowpack between 1950 and 1999 were induced by humans. In this region, conversion of abandoned farmland to pine forests is projected to have a slight surface cooling effect, with evapotranspiration outweighing decreased albedo.

National climate change

In July 2012, the National Oceanic and Atmospheric Administration (NOAA) reported that the 12-month period July 2011 to June 2012 was the warmest 12-month period on record in the continental United States, with average temperature 3.23 °F above the average for the 20th century. Earlier it was reported that exceptionally warm months between January and May 2012 had made the 12 month previous to June 2012 the warmest 12-month block since record keeping began, but this record was exceeded by the July 2011 to June 2012 period. NOAA stated that the odds of the July 2011 to June 2012 high temperatures occurring randomly was 1 in 1,594,323.

From 1898 through 1913, there have been 27 cold waves which totaled 58 days. Between 1970 and 1989, there were about 12 such events. From 1989 until January 6, 2014, there were none. The one on the latter date caused consternation because of decreased frequency of such experiences.

Climate change by state

Alaska

Further information: Climate change in the Arctic

Alaska has seen effects of global warming. The United States Coast Guard officials expect to expand activities as global warming melts these once ice-locked waters.

California

Main article: Climate change in California

California has taken legislative steps towards reducing the possible effects climate change by incentives and plans for clean cars, renewable energy and stringent caps on big polluting industries. In September 2006, the California State Legislature passed AB 32, the Global Warming Solutions Act of 2006 with the goal of reducing man-made California greenhouse gas emissions (1.4% of global emissions in 2004) back to 1990 emission levels by 2020. The legislation grants the Air Resource Board extraordinary powers to set policies, draw up regulations, lead the enforcement effort, levy fines and fees to finance it and punish violators. The technical and regulatory requirements are far reaching. Some of this sweeping regulation is being challenged in the courts. The law is intended to make low-carbon technology more attractive, and promote its adoption in production in California.

While California's claims of successful energy efficiency policy have been widely accepted, a 2013 study argued external factors explained ~95% of the appearance of California's relative efficiency gains. The report cited three key factors: relatively large household size; relatively low household income growth; and US population shift to the Southwest (which increased the average per-capita energy use for the other 49 states).

In California, authorities have predicted that the shortage of rain will increase the duration of the fire season, and result in larger fires. Half of the most destructive fires in recorded California history have occurred since 2002. Climate change and intensifying droughts are drying out landscapes. Pests, such as the mountain pine beetle, have killed off stands of trees.

Colorado

Colorado may be facing a shrinking ski season and an impaired agriculture industry.

Idaho

Main article: Climate change in Idaho

Idaho emits the least carbon dioxide per person of the United States, less than 23,000 pounds a year. Idaho forbids coal-power plants. It relies mostly on nonpolluting hydroelectric power from its rivers. Over the last century, the average temperature near Boise, Idaho, has increased nearly 1 °F, and precipitation has increased by nearly 20% in many parts of the state, and has declined in other parts of the state by more than 10%. Over the next century, climate in Idaho could experience additional changes. For example, based on projections made by the Intergovernmental Panel on Climate Change and results from the United Kingdom Hadley Centre’s climate model (HadCM2), a model that accounts for both greenhouse gases and aerosols, by 2100 temperatures in Idaho could increase by 5 °F (2.8 °C) (with a range of 2-9 °F) in winter and summer and 4 °F (2.2 °C) (with a range of 2-7 °F) in spring and fall.

Massachusetts

Main article: Climate change in Massachusetts

Massachusetts Governor Deval Patrick has recently signed into law three global warming and energy-related bills that will promote advanced biofuels, support the growth of the clean energy technology industry, and cut the emissions of greenhouse gases within the state. The Clean Energy Biofuels Act, signed in late July, exempts cellulosic ethanol from the state's gasoline tax, but only if the ethanol achieves a 60% reduction in greenhouse gas emissions relative to gasoline. The act also requires all diesel motor fuels and all No. 2 fuel oil sold for heating to include at least 2% "substitute fuel" by July 2010, where substitute fuel is defined as a fuel derived from renewable non-food biomass that achieves at least a 50% reduction in greenhouse gas emissions. In early 2008 August, Governor Patrick signed two additional bills: the Green Jobs Act and the Global Warming Solutions Act. The Green Jobs Act will support the growth of a clean energy technology industry within the state, backed by $68 million in funding over 5 years. The Global Warming Solutions Act requires a reduction of greenhouse gas emissions in the state to 10%-25% below 1990 levels by 2020 and to 80% below 1990 levels by 2050.

Nevada

Main article: Climate change in Nevada

Climate change in Nevada has been measured over the last century, with the average temperature in Elko, Nevada, increasing 0.6 °F (0.3 °C), and precipitation has increased by up to 20% in many parts of the state. Based on projections made by the Intergovernmental Panel on Climate Change and results from the Hadley Centre for Climate Prediction and Research climate model (HadCM2), a model that accounts for both greenhouse gases and aerosols, by 2100, temperatures in Nevada could increase by 3-4 °F (1.7-2.2 °C) in spring and fall (with a range of 1-6 °F [0.5-3.3 °C]), and by 5-6 °F (2.8-3.3 °C) in winter and summer (with a range of 2-10 °F [1.1-5.6 °C]). Earlier and more rapid snowmelts could contribute to winter and spring flooding, and more intense summer storms could increase the likelihood of flash floods. Climate change could have an impact on crop production, reducing potato yields by about 12%, with hay and pasture yields increasing by about 7%. Farmed acres could rise by 9% or fall by 9%, depending on how climate changes. The region's inherently variable and unpredictable hydrological and climatic systems could become even more variable with changes in climate, putting stress on wetland ecosystems. A warmer climate would increase evaporation and shorten the snow season in the mountains, resulting in earlier spring runoff and reduced summer streamflow. This would exacerbate fire risk in the late summer. Many desert-adapted plants and animals already live near their tolerance limits, and could disappear under the hotter conditions predicted under global warming.

New York

Main article: Climate change in New York City

Climate change in New York City could affect buildings/structures, wetlands, water supply, health, and energy demand, due to the high population and extensive infrastructure in the region. New York is especially at risk if the sea level rises, due to many of the bridges connecting to boroughs, and entrances to roads and rail tunnels. High-traffic locations such as the airports, the Holland Tunnel, the Lincoln Tunnel, and the Passenger Ship Terminal are located in areas vulnerable to flooding. Flooding would be expensive to reverse. New York has launched a task force to advise on preparing city infrastructure for flooding, water shortages, and higher temperatures.

Texas

Main article: Climate change in Texas

Over the next century, climate in Texas could experience additional changes. For example, based on projections made by the Intergovernmental Panel on Climate Change and results from the United Kingdom Hadley Centre’s climate model (HadCM2), a model that accounts for both greenhouse gases and aerosols, by 2100 temperatures in Texas could increase by about 3 °F (~1.7 °C) in spring (with a range of 1-6 °F) and about 4 °F (~2.2 °C) in other seasons (with a range of 1-9 °F). Texas emits more carbon dioxide into the atmosphere than any other state. And if Texas were a country, it would be the seventh-largest carbon dioxide polluter in the world . Texas's high carbon dioxide output and large energy consumption is primarily a result of large coal-burning power plants and gas-guzzling vehicles (low miles per gallon). Unless increased temperatures are coupled with a strong increase in rainfall, water could become more scarce. A warmer and drier climate would lead to greater evaporation, as much as a 35% decrease in streamflow, and less water for recharging groundwater aquifers. Climate change could reduce cotton and sorghum yields by 2-15% and wheat yields by 43-68%, leading to changes in acres farmed and production. With changes in climate, the extent and density of forested areas in east Texas could change little or decline by 50-70%. Hotter, drier weather could increase wildfires and the susceptibility of pine forests to pine bark beetles and other pests, which would reduce forests and expand grasslands and arid shrublands.

Washington

Main article: Climate change in Washington

Visible physical impacts on the environment within WA State include glacier reduction, declining snow-pack, earlier spring runoff, an increase in large wildfires, and rising sea levels which affect the Puget Sound area. Less snow pack will also result in a time change of water flow volumes into fresh water systems, resulting in greater winter river volume, and less volume during summer's driest months, generally from July through October. These changes will result in both economic and ecological repercussions, most notably found in hydrological power output, municipal water supply and migration of fish. Collectively, these changes are negatively affecting agriculture, forest resources, dairy farming, the WA wine industry, electricity, water supply, and other areas of the state. Beyond affecting wildfires, climate change could impact the economic contribution of Washington’s forests both directly (e.g., by affecting rates of tree growth and relative importance of different tree species) and indirectly (e.g., through impacts on the magnitude of pest or fire damage). Beyond growth rates, climate change could affect Washington forests by changing the range and life cycle of pests.

Washington State currently relies on hydro power for 72% of its power and sales of hydro power to both households and businesses topped 4.3 billion dollars in 2003. Washington State currently has the 9th lowest cost for electricity in the US. Climate change will have a negative effect on both the supply and demand of electricity in Washington. The available electricity supply could also be affected by climate change. Currently, peak stream flows are in the summer. Snowpack is likely to melt earlier in the future due to increased temperatures, thus shifting the peak stream flow to late winter and early spring, with decreased summer stream flow. This would result in an increased availability of electricity in the early spring, when demand is dampened, and a decreased availability in the summer, when the demand may be highest.

West Virginia

Main article: Climate change in West Virginia

Warming and other climate changes could expand the habitat and infectiousness of disease-carrying insects, thus increasing the potential for transmission of diseases such as malaria and dengue (“break bone”) fever. Warmer temperatures could increase the incidence of Lyme disease and other tick-borne diseases in West Virginia, because populations of ticks, and their rodent hosts, could increase under warmer temperatures and increased vegetation. Lower streamflows and lake levels in the summer and fall could affect the dependability of surface water supplies, particularly since many of the streams in West Virginia have low flows in the summer. Hay yields could increase by about 30% as a result of climate change, leading to changes in acres farmed and production. Farmed acres could remain constant or could decrease by as much as 30% in response to changes in prices, for example, possible decreases in hay prices. In areas where richer soils are prevalent, southern pines could increase their range and density, and in areas with poorer soils, which are more common in West Virginia’s forests, scrub oaks of little commercial value (e.g., post oak and blackjack oak) could increase their range. As a result, the character of forests in West Virginia could change. The state of West Virginia is 97% forested, and much of this cover is in high-elevation areas. These areas contain some of the last remaining stands of red spruce, which are seriously threatened by acid rain and could be further stressed by changing climate. Given a sufficient change in climate, these spruce forests could be substantially reduced, or could disappear. Higher-than-normal winter temperatures could boost temperatures inside cave bat roosting sites, which has been shown to cause higher mortality due to increased winter body weight loss in endangered Indiana bats (e.g., an increase of 9 °F (−13 °C) during winter hibernation has been associated with a 42% increase in the rate of body mass loss).

Wyoming

Main article: Climate change in Wyoming

On a per-person basis, Wyoming emits more carbon dioxide than any other state or any other country: 276,000 pounds (125,000 kg) of it per capita a year, because of burning coal, which provides nearly all of the state's electrical power. Warmer temperatures could increase the incidence of Lyme disease and other tick-borne diseases in Wyoming, because populations of ticks, and their rodent hosts, could increase under warmer temperatures and increased vegetation. Increased runoff from heavy rainfall could increase water-borne diseases such as giardia, cryptosporidia, and viral and bacterial gastroenteritis. The headwaters of several rivers originate in Wyoming and flow in all directions into the Missouri, Snake, and Colorado River basins. A warmer climate could result in less winter snowfall, more winter rain, and faster, earlier spring snowmelt. In the summer, without increases in rainfall of at least 15-20%, higher temperatures and increased evaporation could lower streamflows and lake levels. Less water would be available to support irrigation, hydropower generation, public water supplies, fish and wildlife habitat, recreation, and mining. Hotter, drier weather could increase the frequency and intensity of wildfires, threatening both property and forests. Drier conditions would reduce the range and health of ponderosa and lodgepole forests, and increase their susceptibility to fire. Climate change also poses a threat to the high alpine systems, and this zone could disappear in many areas. Local extinctions of alpine species such as arctic gentian, alpine chaenactis, rosy finch, and water pipit could be expected as a result of habitat loss and fragmentation. In cooperation with the Wyoming Business Council, the Converse Area New Development Organization drafted an initiative to advance geothermal energy development in Wyoming. The Wyoming Business Council offers grants for homeowners who want to install photovoltaic (PV) systems.

Multiple states

Sea level rise affects multiple states. States have undertaken a variety of initiatives to plan for the impacts of sea level rise. But because the impacts of sea level rise vary significantly from region to region, many planning initiatives take place at the local level.

See also

• 2010–2012 Southern United States drought
• Climate change in the European Union
• Coal in the United States
• Energy conservation in the United States
• Environmental issues in the United States
• Hurricane Katrina and global warming
• List of countries by greenhouse gas emissions per capita
• Major Economies Forum on Energy and Climate
• National Climate Assessment
• Public opinion on climate change
• Regional Clean Air Incentives Market (RECLAIM, an emission trading scheme in California)
• Renewable energy in the United States
• U.S. Climate Change Science Program

External links

• Global Climate Change Impacts in the United States edited by Tom Karl National Oceanic and Atmospheric Administration, Asheville, North Carolina, Jerry Melillo Marine Biological Laboratory, Woods Hole, Thomas C. Peterson National Oceanic and Atmospheric Administration, Asheville, North Carolina, and Susan Joy Hassol; Climate Communication, Basalt, Colorado. Summarizes the science of climate change and impacts on the United States, for the public and policymakers. ISBN 978-0-521-14407-0
• United States Environmental Protection Agency - climate change page
• Fourth U.S. Climate Action Report to the UN Framework Convention on Climate Change.
• U.S. Climate Report Details Energy, Agriculture Harm
• Warming Marches in; March 2012 was the balmiest on record for the continental United States, setting a mountain of new records April 10, 2012
• Now Do You Believe in Global Warming? July 10, 2012 Time
• Endless Summer July 23, 2012 Time
• Storms Threaten Ozone Layer Over U.S., Study Says July 26, 2012 New York Times, regarding ozone depletion and the effects of global warming
• Climate and Social Stress: Implications for Security Analysis (2012) National Academies Press
• Climate Change Report Outlines Perils for U.S. Military. The New York Times. November 9, 2012.
• NASA: Global Climate Change