This, in turn, will cause a series of linked environmental responses in which other currently rising trends reverse one by one in a "climate whiplash" phase that follows the lead of our carbon emissions. For example, as CO 2 dissolves into the oceans, it combines with water to form carbonic acid, which alters the chemistry of seawater and makes limestone, chalk, and other carbonate-rich substances more likely to dissolve.
Ocean acidification will peak shortly after atmospheric CO 2 concentrations do, threatening marine species that have acid-soluble carbonate shells or skeletons, including corals, shellfish, and crustaceans Figure 1. Figure 1: Staghorn coral near Key West, Florida. Ocean acidification threatens these and other marine organisms that depend on acid-soluble carbonate supporting structures and shells.
Some rights reserved. After a delay due to slow response times in the atmosphere and oceans Wigley , global average temperatures will pivot into cooling mode as CO 2 concentrations continue to fall. However, global mean sea level will still rise long after the thermal peak passes, because even though temperatures will be falling, they will still be warmer than today.
Therefore, land-based glacial ice will continue to melt and the oceans will continue to expand even though Earth's atmosphere has begun to recover. Sea level will only return to today's position when it finally becomes cool enough for large, land-based ice sheets to build up again on Antarctica and in the Arctic.
In order to work out the timing of these processes in more detail, one must consider where CO 2 goes after it leaves our smokestacks and exhaust pipes. Some of it will be taken up by soils and organisms but most of it will dissolve into the oceans, with between two thirds and half of our emissions perhaps going into solution during the next millennium or so Inman , Eby et al.
In many computer simulations, maximum ocean acidification lasts years or more, depending on the amount of CO 2 we emit in the near future. Marine species living in the polar regions and deep sea basins and trenches will be the most rapidly and severely impacted because the solubility of such gases is greatest in cold waters.
But after the seas have absorbed as much CO 2 as they can, roughly a fifth of our fossil carbon emissions will still be left adrift in the air Tyrell et al. The next stage of the cleanup will proceed more slowly. As atmospheric CO 2 dissolves into raindrops, the carbonic acid that it produces will react with calcite and other carbonate minerals in rocks and sediments. Over thousands of years, those geochemical weathering processes will transfer many of the formerly airborne carbon atoms into groundwater and runoff, finally delivering them to the oceans in the form of dissolved bicarbonate and carbonate ions.
Meanwhile, carbonate-rich deposits on the sea floor will experience similar reactions with overlying seawater as the oceans become more acidified. This slow addition of acid-buffering substances to marine ecosystems will act much like an antacid pill that allows the seas to consume more CO 2 from the overlying atmosphere.
These processes are generally expected to dominate the long-term recovery for 5, years or so. But even this second, lengthier phase won't remove the very last fraction of our carbon pollution. Only tens of thousands of years later, or possibly even hundreds of thousands if we burn most of our enormous coal reserves, the last remnants of our CO 2 will finally be scrubbed away by even slower reactions with resistant silicate minerals, such as the feldspars found in granite and basalt.
This is what University of Chicago oceanographer David Archer calls "the long tail of the carbon curve" Archer , and it will be dominated by gradual global cooling , albeit at higher temperatures than those of today. The intensity and duration of the warming peak and recovery will depend upon choices we make during this century. Figure 2: Airborne carbon dioxide concentrations in a moderate emissions scenario.
Note the steep initial rise, rapid climate whiplash turnaround, and slow long-term recovery over the next , years. All rights reserved. Much of Greenland and western Antarctica's ice will melt into the oceans over millennia, lifting sea levels several meters higher than today before slowly receding.
On the other hand, if we burn through all remaining coal reserves before switching to alternative energy sources, then a far more extreme scenario will result. In one computer simulation of what could follow a gigaton emission Figure 3; Schmittner et al. Atmospheric CO 2 concentrations and temperatures then fall relatively steeply for several thousand years after the peak and whiplash phase, but they don't return to today's levels for at least , years.
All land-based ice eventually melts, raising sea levels by as much as 70 meters until the world cools enough for large polar ice sheets to form again, roughly half a million years from now. Figure 3 Detail of the first years of an extreme emissions scenario, showing lagged responses of atmospheric CO2 concentrations, temperatures, and sea level.
What might life on Earth be like under such conditions? Although no examples from the past perfectly illustrate the warmest phases of these two scenarios, several of them are nonetheless informative. The surface area of the Greenland ice sheet shrank by at least a third, the Arctic Ocean lost some summer ice-cover but retained enough for ringed seals and polar bears to survive, elephants and water buffalo migrated northward into Britain and Europe, and trees that are now more typical of the southeastern United States, such as black gums and hickories, thrived in the Adirondack Mountains of upstate New York Stager Although it was caused by cyclic changes in the orientation of the Earth relative to the sun rather than greenhouse gases, the Eemian example nonetheless shows that even a relatively moderate warming can melt enough land-based ice to raise sea levels by 6—9 meters if it persists long enough, which in this case was 13, years Figure 4.
Figure 4: Fossil oysters resting several meters above the surf zone near Durban, South Africa. Their elevation shows how high sea level once stood during the warm Eemian Interglacial, ,—, years ago. The more extreme of the two emissions scenarios is better illustrated by a super-hothouse that occurred 55 million years ago-roughly 10 million years after the demise of the dinosaurs.
Geo-historical evidence shows that the Paleocene-Eocene Thermal Maximum PETM was triggered by greenhouse gas buildups, most likely from the release of icy methane hydrates or other carbon compounds buried in marine deposits Katz et al.
Both polar regions were completely ice-free, the Arctic Ocean was a warm, brackish pond rimmed by deciduous redwood forests, Antarctica was covered by beech trees, and carbonic acid burned a discolored, carbonate-free band into ocean sediments worldwide Zachos et al.
Some species became extinct during the PETM, especially in the most heavily acid-impacted portions of the oceans Gibbs et al. Such long-term perspectives are not only scientifically interesting and important, they also raise new ethical questions, simply because human beings are now in the picture. Our carbon emissions will influence countless generations, as well as many species other than our own, in future versions of the world that will differ markedly from the one we know now.
This realization may force us to weigh the needs of some generations against those of others. For instance, having the Arctic Ocean become ice-free in summer may seem outlandish to us, but it may instead seem normal to people who will be born into a warmer world thousands of years from now. Climate change has accelerated the rate of ice loss across the continent.
Read next: Is Global Warming Real? All rights reserved. And how does it relate to global warming? Learn about the impact and consequences of climate change and global warming for the environment and our lives.
This includes mountain glaciers, ice sheets covering West Antarctica and Greenland, and Arctic sea ice. In Montana's Glacier National Park the number of glaciers has declined to fewer than 30 from more than in Much of this melting ice contributes to sea-level rise. Global sea levels are rising 0. Rising temperatures are affecting wildlife and their habitats. As temperatures change, many species are on the move. Some butterflies, foxes, and alpine plants have migrated farther north or to higher, cooler areas.
Precipitation rain and snowfall has increased across the globe, on average. As the heat waves, droughts, and floods associated with climate change become more frequent and more intense, communities suffer and death tolls rise. Global warming is already taking a toll on the United States. Though everyone is affected by climate change, not everyone is affected equally. Indigenous people, people of color, and the economically marginalized are typically hit the hardest.
Inequities built into our housing , health care , and labor systems make these communities more vulnerable to the worst impacts of climate change—even though these same communities have done the least to contribute to it. A: In recent years, China has taken the lead in global-warming pollution , producing about 26 percent of all CO2 emissions.
The United States comes in second. And America is still number one, by far, in cumulative emissions over the past years. As a top contributor to global warming, the United States has an obligation to help propel the world to a cleaner, safer, and more equitable future. Our responsibility matters to other countries, and it should matter to us, too. But in order to avoid the worsening effects of climate change, we need to do a lot more—together with other countries—to reduce our dependence on fossil fuels and transition to clean energy sources.
Despite the lack of cooperation from the Trump administration, local and state governments made great strides during this period through efforts like the American Cities Climate Challenge and ongoing collaborations like the Regional Greenhouse Gas Initiative. Meanwhile, industry and business leaders have been working with the public sector, creating and adopting new clean-energy technologies and increasing energy efficiency in buildings, appliances, and industrial processes.
Today the American automotive industry is finding new ways to produce cars and trucks that are more fuel efficient and is committing itself to putting more and more zero-emission electric vehicles on the road. Developers, cities, and community advocates are coming together to make sure that new affordable housing is built with efficiency in mind , reducing energy consumption and lowering electric and heating bills for residents.
And renewable energy continues to surge as the costs associated with its production and distribution keep falling. In renewable energy sources such as wind and solar provided more electricity than coal for the very first time in U. President Biden has made action on global warming a high priority.
Many people insist that the few fish that are left should be enjoyed while they last—an argument, hard to fault in many parts of the world, that applies to so much that is vanishing.
As devastating as rising oceans have been, droughts and heat waves inland have created a special hell.
Vast regions have succumbed to severe aridification, sometimes followed by desertification. Wildlife there has become a distant memory.
Cities such as Marrakech and Volgograd are on the verge of becoming deserts. Hong Kong, Barcelona, Abu Dhabi, and many others have been desalinating seawater for years, desperately trying to keep up with the constant wave of immigration from areas that have gone completely dry.
Extreme heat is on the march. This is no longer the headline-grabbing event it would have been 30 years ago. Everyone stays inside, drinks water, and dreams of air-conditioning. You lie on your couch, a cold, wet towel over your face, and try to rest without dwelling on the poor farmers on the outskirts of town who, despite recurrent droughts and wildfires, are still trying to grow grapes, olives, or soy—luxuries for the rich, not for you.
Places such as central India are becoming increasingly challenging to inhabit. Mass migrations to less hot rural areas are beset by a host of refugee problems, civil unrest, and bloodshed over diminished water availability. Even in some parts of the United States, there are fiery conflicts over water, battles between the rich who are willing to pay for as much water as they want and everyone else demanding equal access to the life-enabling resource. The taps in nearly all public facilities are locked, and those in restrooms are coin-operated.
At the federal level, Congress is in an uproar over water redistribution: states with less water demand what they see as their fair share from states that have more. Government leaders have been stymied on the issue for years, and with every passing month the Colorado River and the Rio Grande shrink further. Food production swings wildly from month to month, season to season, depending on where you live. More people are starving than ever before. Climate zones have shifted, so some new areas have become available for agriculture Alaska, the Arctic , while others have dried up Mexico, California.
Still others are unstable because of the extreme heat, never mind flooding, wildfire, and tornadoes.
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