Residents of Ogden, Utah, clear snow after close to a foot fell in the area Friday. A federal report on climate change described devastating weather linked to global warming. (Nick Short, Associated Press / ) 
 
 WASHINGTON — The impacts of climate change driven by human activity are spreading through the United States faster than had been predicted, increasingly threatening infrastructure, water supplies, crops and shorelines, according to a federal advisory committee. 
 
 The draft Third National Climate Assessment, issued every four years, delivers a bracing picture of environmental changes and natural disasters that mounting scientific evidence indicates is fostered by climate change: heavier rains in the Northeast, Midwest and Plains that have overwhelmed storm drains and led to flooding and erosion; sea level rise that has battered coastal communities; drought that has turned much of the West into a tinderbox. 
 
 "Climate change, once considered an issue for a distant future, has moved firmly into the present," the report says. "Americans are noticing changes all around them. Summers are longer and hotter, and periods of extreme heat last longer than any living American has ever experienced. Winters are generally shorter and warmer." 
 
 Written by 240 scientists, business leaders and other experts, the draft assessment arrives days after the National Oceanic and Atmospheric Administration issued its annual State of the Climate Report, which noted that 2012 was the hottest year on record. Together, the two major reports and a year of drought, wildfires, floods and freak storms have created for President Obama the chance to take substantial steps on climate change, environmentalists said. 
 
 The report explicitly addresses the most controversial question in the global warming issue, saying that consumption of fossil fuels by humans is the main driver of climate change. 
 
 "The findings in the report are a three-alarm fire," said Rep. Henry A. Waxman (D-Beverly Hills). "Climate change is already causing widespread disruption across the nation. We are in deep trouble if we don't act forcefully this year." 
 
 But with the White House working on so many economic, foreign and domestic policy fronts, it remains unclear if the president will speak up more on climate, let alone spearhead new initiatives. 
 
 The Obama administration has implemented several regulations to curtail emissions of carbon dioxide and other greenhouse gases that scientists say have stoked global warming. But the president seldom speaks of climate change. 
 
 The White House declined to comment on the National Climate Assessment report, saying it had not had a chance to review it. 
 
 The report, issued by an independent, interagency group operating under the president's National Science and Technology Council, first came out in 2000 but went on hiatus during the Bush administration. It does not offer policy proposals to reduce greenhouse gas emissions or to help specific communities adapt to climate change. Instead, it details the risks they face. 
 
 The Southwest, including California, produces more than half of the country's "high-value specialty" crops that are heavily dependent on irrigation. But a projected decline in snowpack and stream flow and increased competition for the water could threaten California's agricultural communities. Higher temperatures could disrupt regional electricity grids and create public health emergencies in Southwestern cities, where 90% of the region's population lives. 
 
 Flooding and sea level rise are already damaging some coastal California communities during storms and high tides, the assessment says, and water would come farther inland as erosion worsens. 
 
 The final assessment will be issued in early 2014. Public comment on the draft will be accepted until April 12. 
 
 neela.banerjee@latimes.com ||||| The potential future effects of global climate change include more frequent wildfires, longer periods of drought in some regions and an increase in the number, duration and intensity of tropical storms. Credit: Left - Mellimage/Shutterstock.com, center - Montree Hanlue/Shutterstock.com. 
 
 Global climate change has already had observable effects on the environment. Glaciers have shrunk, ice on rivers and lakes is breaking up earlier, plant and animal ranges have shifted and trees are flowering sooner. 
 
 Effects that scientists had predicted in the past would result from global climate change are now occurring: loss of sea ice, accelerated sea level rise and longer, more intense heat waves. 
 
 Taken as a whole, the range of published evidence indicates that the net damage costs of climate change are likely to be significant and to increase over time. - Intergovernmental Panel on Climate Change 
 
 Scientists have high confidence that global temperatures will continue to rise for decades to come, largely due to greenhouse gases produced by human activities. The Intergovernmental Panel on Climate Change (IPCC), which includes more than 1,300 scientists from the United States and other countries, forecasts a temperature rise of 2.5 to 10 degrees Fahrenheit over the next century. 
 
 According to the IPCC, the extent of climate change effects on individual regions will vary over time and with the ability of different societal and environmental systems to mitigate or adapt to change. 
 
 The IPCC predicts that increases in global mean temperature of less than 1.8 to 5.4 degrees Fahrenheit (1 to 3 degrees Celsius) above 1990 levels will produce beneficial impacts in some regions and harmful ones in others. Net annual costs will increase over time as global temperatures increase. 
 
 "Taken as a whole," the IPCC states, "the range of published evidence indicates that the net damage costs of climate change are likely to be significant and to increase over time." 1-2 
 
 Future effects 
 
 Some of the long-term effects of global climate change in the United States are as follows, according to the Third and Fourth National Climate Assessment Reports: 
 
 Change will continue through this century and beyond 
 
 Global climate is projected to continue to change over this century and beyond. The magnitude of climate change beyond the next few decades depends primarily on the amount of heat-trapping gases emitted globally, and how sensitive the Earth’s climate is to those emissions. 
 
 Temperatures will continue to rise 
 
 Because human-induced warming is superimposed on a naturally varying climate, the temperature rise has not been, and will not be, uniform or smooth across the country or over time. 
 
 Frost-free season (and growing season) will lengthen 
 
 The length of the frost-free season (and the corresponding growing season) has been increasing nationally since the 1980s, with the largest increases occurring in the western United States, affecting ecosystems and agriculture. Across the United States, the growing season is projected to continue to lengthen. 
 
 
 
 In a future in which heat-trapping gas emissions continue to grow, increases of a month or more in the lengths of the frost-free and growing seasons are projected across most of the U.S. by the end of the century, with slightly smaller increases in the northern Great Plains. The largest increases in the frost-free season (more than eight weeks) are projected for the western U.S., particularly in high elevation and coastal areas. The increases will be considerably smaller if heat-trapping gas emissions are reduced. 
 
 + more Visualization comparing 1950s and 2010s This NASA visualization presents observational evidence that the growing season (climatological spring) is occurring earlier in the Northern Hemisphere. 
 
 Changes in precipitation patterns 
 
 Average U.S. precipitation has increased since 1900, but some areas have had increases greater than the national average, and some areas have had decreases. More winter and spring precipitation is projected for the northern United States, and less for the Southwest, over this century. 
 
 
 
 Projections of future climate over the U.S. suggest that the recent trend towards increased heavy precipitation events will continue. This trend is projected to occur even in regions where total precipitation is expected to decrease, such as the Southwest. 
 
 + more NASA visualizations of future precipitation scenarios These NASA visualizations show model projections of the precipitation changes from 2000 to 2100 as a percentage difference between the 30-year precipitation averages and the 1970-1999 average. 
 
 Precipitation Measurement Missions The official website for NASA's fleet of Earth science missions that study rainfall and other types precipitation around the globe. 
 
 Precipitation quiz Earth’s water is stored in ice and snow, lakes and rivers, the atmosphere and the oceans. How much do you know about Earth's water cycle and the crucial role it plays in our climate? 
 
 More droughts and heat waves 
 
 Droughts in the Southwest and heat waves (periods of abnormally hot weather lasting days to weeks) everywhere are projected to become more intense, and cold waves less intense everywhere. 
 
 
 
 Summer temperatures are projected to continue rising, and a reduction of soil moisture, which exacerbates heat waves, is projected for much of the western and central U.S. in summer. By the end of this century, what have been once-in-20-year extreme heat days (one-day events) are projected to occur every two or three years over most of the nation. 
 
 + more NASA visualizations of future precipitation scenarios These NASA visualizations show model projections of the precipitation changes from 2000 to 2100 as a percentage difference between the 30-year precipitation averages and the 1970-1999 average. 
 
 NASA: Megadroughts in U.S. West projected to be worst of millennium Droughts in the Southwest and Central Plains of the United States in the second half of the 21st century could be drier and longer than anything humans have seen in those regions in the last 1,000 years, according to a NASA study published in Science Advances on February 12, 2015. 
 
 Hurricanes will become stronger and more intense 
 
 The intensity, frequency and duration of North Atlantic hurricanes, as well as the frequency of the strongest (Category 4 and 5) hurricanes, have all increased since the early 1980s. The relative contributions of human and natural causes to these increases are still uncertain. Hurricane-associated storm intensity and rainfall rates are projected to increase as the climate continues to warm. 
 
 + more NASA: What are the chances of another Hurricane Katrina? According to a new NASA study, a string of nine years without a major hurricane landfall in the U.S. is Iikely to come along only once every 177 years. This video explains the findings of this study. 
 
 Sea level will rise 1-4 feet by 2100 
 
 Global sea level has risen by about 8 inches since reliable record keeping began in 1880. It is projected to rise another 1 to 4 feet by 2100. This is the result of added water from melting land ice and the expansion of seawater as it warms. 
 
 
 
 In the next several decades, storm surges and high tides could combine with sea level rise and land subsidence to further increase flooding in many regions. Sea level rise will continue past 2100 because the oceans take a very long time to respond to warmer conditions at the Earth’s surface. Ocean waters will therefore continue to warm and sea level will continue to rise for many centuries at rates equal to or higher than those of the current century. 
 
 Arctic likely to become ice-free 
 
 The Arctic Ocean is expected to become essentially ice free in summer before mid-century. 
 
 + more Earth’s vital signs: Sea ice An indicator of changes in the Arctic sea ice minimum over time. Arctic sea ice extent both affects and is affected by global climate change. 
 
 Global Ice Viewer An interactive exploration of how global warming is affecting sea ice, glaciers and continental ice sheets worldwide. 
 
 U.S. regional effects 
 
 Below are some of the impacts that are currently visible throughout the U.S. and will continue to affect these regions, according to the Third3 and Fourth4 National Climate Assessment Reports, released by the U.S. Global Change Research Program: 
 
 Northeast. Heat waves, heavy downpours and sea level rise pose growing challenges to many aspects of life in the Northeast. Infrastructure, agriculture, fisheries and ecosystems will be increasingly compromised. Many states and cities are beginning to incorporate climate change into their planning. 
 
 Northwest. Changes in the timing of streamflow reduce water supplies for competing demands. Sea level rise, erosion, inundation, risks to infrastructure and increasing ocean acidity pose major threats. Increasing wildfire, insect outbreaks and tree diseases are causing widespread tree die-off. 
 
 Southeast. Sea level rise poses widespread and continuing threats to the region’s economy and environment. Extreme heat will affect health, energy, agriculture and more. Decreased water availability will have economic and environmental impacts. 
 
 Midwest. Extreme heat, heavy downpours and flooding will affect infrastructure, health, agriculture, forestry, transportation, air and water quality, and more. Climate change will also exacerbate a range of risks to the Great Lakes. 
 
 Southwest. Increased heat, drought and insect outbreaks, all linked to climate change, have increased wildfires. Declining water supplies, reduced agricultural yields, health impacts in cities due to heat, and flooding and erosion in coastal areas are additional concerns. 
 
 References ||||| Major report warns climate change could raise temperatures by 10 degrees By Ben Geman - Tweet A major draft federal report concludes that climate change is already affecting U.S. residents through heat waves, droughts and other changes, and warns that temperatures could increase as much as 10 degrees Fahrenheit if global carbon emissions keep soaring. 
 
 The third National Climate Assessment, released Friday, said there’s “unambiguous evidence” that earth is warming, and that climate change over the past 50 years is driven primarily by human activity, especially from burning fossil fuels. 
 
 
 
 “Certain types of weather events have become more frequent and/or intense, including heat waves, heavy downpours, and, in some regions, floods and droughts. Sea level is rising, oceans are becoming more acidic, and glaciers and arctic sea ice are melting,” states the draft report developed by a federal advisory panel. 
 
 
 
 “These changes are part of the pattern of global climate change, which is primarily driven by human activity,” adds the draft report, released through U.S. Global Change Research Program. 
 
 
 
 It also tallies regional effects of climate change in the U.S. 
 
 
 
 Environmentalists quickly seized on the report, which follows a separate federal announcement that 2012 was the hottest year on record in the lower 48 states, to call for more aggressive steps to drive down emissions. 
 
 
 
 “This could help restart a national conversation about climate change,” said Todd Sanford, a scientist with the Union of Concerned Scientists. “It gives us a road map for climate change. And the road is much bumpier if we continue along a higher emissions pathway.” 
 
 
 
 Carol Browner, President Obama’s former climate czar, said the U.S. has made progress in reducing emissions but more action is needed immediately. 
 
 
 
 “We can start with strict carbon pollution standards for power plants and we must significantly expand investments in community resiliency to protect people and the economy from the gathering storms — and floods, droughts, wildfires, and heat waves,” said Browner, who is now a senior fellow with the liberal Center for American Progress. 
 
 
 
 The report finds that U.S. temperatures will continue rising 2 degrees F to 4 degrees F in most areas in the coming decades, and calls for effort to increase resilience to changes that cannot be avoided. 
 
 
 
 But it’s unclear how high temperatures will climb. The report provides a range of 3 degrees F to 5 degrees F by century's end if global emissions are reduced sharply after 2050, and up to 10 degrees F if they’re not. 
 
 
 
 Average U.S. temperatures have risen roughly 1.5 degrees F since 1895, and more than 80 percent of that increase has occurred since 1980, the report concludes. 
 
 
 
 The report is just the latest broad study or statement by a scientific body to conclude there’s overwhelming evidence that global warming is under way and that human activities are a major cause. 
 
 
 
 For instance, the National Research Council, in a The report tallies the wide-ranging effects of climate change, such as water supplies stressed by declining runoff and increased risk of heat stress and waterborne disease, and notes that U.S. infrastructure is already being harmed by sea-level rise, storm surges and heavy downpours.It also tallies regional effects of climate change in the U.S.Environmentalists quickly seized on the report, which follows a separate federal announcement that 2012 was the hottest year on record in the lower 48 states, to call for more aggressive steps to drive down emissions.“This could help restart a national conversation about climate change,” said Todd Sanford, a scientist with the Union of Concerned Scientists. “It gives us a road map for climate change. And the road is much bumpier if we continue along a higher emissions pathway.”Carol Browner, President Obama’s former climate czar, said the U.S. has made progress in reducing emissions but more action is needed immediately.“We can start with strict carbon pollution standards for power plants and we must significantly expand investments in community resiliency to protect people and the economy from the gathering storms — and floods, droughts, wildfires, and heat waves,” said Browner, who is now a senior fellow with the liberal Center for American Progress.The report finds that U.S. temperatures will continue rising 2 degrees F to 4 degrees F in most areas in the coming decades, and calls for effort to increase resilience to changes that cannot be avoided.But it’s unclear how high temperatures will climb. The report provides a range of 3 degrees F to 5 degrees F by century's end if global emissions are reduced sharply after 2050, and up to 10 degrees F if they’re not.Average U.S. temperatures have risen roughly 1.5 degrees F since 1895, and more than 80 percent of that increase has occurred since 1980, the report concludes.The report is just the latest broad study or statement by a scientific body to conclude there’s overwhelming evidence that global warming is under way and that human activities are a major cause.For instance, the National Research Council, in a 2011 report , noted that climate change is “very likely caused primarily” by human-induced greenhouse gas emissions. However, a substantial number of Republicans dispute the conclusion that human activities are the primary driver of climate change. 
 
 
 
 Rep. Lamar Smith (R-Texas), chairman of the House Science, Space and Technology Committee, said in a statement Friday that he plans to vet climate science in the new Congress. 
 
 
 
 “I believe climate change is due to a combination of factors, including natural cycles, sun spots, and human activity. But scientists still don’t know for certain how much each of these factors contributes to the overall climate change that the Earth is experiencing,” he said in a statement Friday. 
 
 
 
 “It is the role of the Science Committee to create a forum for discussion so Congress and the American people can hear from experts and draw reasoned conclusions,” he said. The panel will have a hearing on the environment in coming weeks, according to committee aides. 
 
 
 
 While climate advocates are pouncing on the report, it’s unlikely to fundamentally change the politics of climate change on Capitol Hill, where bills to cap emissions or impose carbon taxes are moribund. 
 
 
 
 However, green activists are pressing for stronger executive actions, such as Environmental Protection Agency carbon emissions standards for existing power plants. 
 
 
 
 The broad new federal assessment was released in draft form Friday by the National Climate Assessment and Development and Advisory Committee, which is comprised of experts from academia, various industries and elsewhere. 
 
 The National Research Council will review the draft, which is also open for public comment. 
 
 
 
 The report was crafted under the Global Change Research Act of 1990, which requires wide-ranging climate reports to the president and Congress. This post was updated at 5:34 p.m. on Jan. 12 
 
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– A federal advisory panel has delivered its assessment on climate change, and it's not pretty. Expect hotter temperatures and more "extreme weather events" across the US in coming decades, says the panel of 240 scientists and other experts, reports the Hill. “These changes are part of the pattern of global climate change, which is primarily driven by human activity,” says the draft report of the National Climate Assessment. (Read it in full here.) Some other highlights: It's a problem now: "Climate change, once considered an issue for a distant future, has moved firmly into the present," says the report. "Americans are noticing changes all around them. Summers are longer and hotter, and periods of extreme heat last longer than any living American has ever experienced. Winters are generally shorter and warmer." Severe weather: “Certain types of weather events have become more frequent and/or intense, including heat waves, heavy downpours, and, in some regions, floods and droughts. Sea level is rising, oceans are becoming more acidic, and glaciers and arctic sea ice are melting." How much hotter? Most of the US will be 2 to 4 degrees Fahrenheit hotter over the coming decades, says the report. Under current emissions, temperatures could rise a staggering 5 to 10 degrees by 2100. The report does not make recommendations on how to fix things, notes the LA Times, but environmentalists and their legislative backers hope the forecast will prompt the White House to move. "The findings in the report are a three-alarm fire," says Democratic congressman Henry Waxman. The last assessment came out in 2009, and "evidence for a changing climate has strengthened considerably" since then, say the authors, reports NPR.