Major Report warns that climate change is accelerating and humans must cut emissions now
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According to Monday's landmark UN report, global climate change is rapidly increasing and human greenhouse gas emissions are the major cause. The authors warn that there is still time to prevent catastrophic warming in the next century. However, this can only be achieved if all countries stop using fossil fuels.
The message to world leaders has never been more urgent and unambiguous.
"It is indisputable, that human activities have caused climate change," said Ko Barrett, vice-chair of U.N. Intergovernmental Panel on Climate Change and senior adviser for climate at U.S. National Oceanic and Atmospheric Administration. "Each of these four decades have been the warmest since pre-industrial time."
Nearly 200 top climate scientists contributed to the report. They hope that it will be prominently discussed at a world leader's meeting in November.
These warming effects are deadly and obvious around the globe. This summer, heat waves, droughts, and floods have caused havoc in the lives of millions around the globe. Wildfires are blazing with unprecedented intensity and frequency, even in places where they used to be rare. People in cities and towns across Asia and the Arctic are being choked by smoke and smog. Ocean heat waves threaten entire ecosystems, and are supercharging hurricanes or typhoons.
Science is clear: Human carbon dioxide and other greenhouse gas emissions are the main driver of these changes.
Extreme weather is caused by human greenhouse gas emissions
The field of "attribution science", which links global warming to specific weather events like heat waves or hurricanes, is one of the most important areas of climate research. Scientists now know that humans are responsible for more extreme weather conditions, such as heavy downpours, extended heat waves, and droughts.
Kim Cobb, a Georgia Institute of Technology paleoclimate scientist and one of the report's authors, says that "this whiplash" is a projected increase in extreme wet events and dry events through the 21st Century.
Every chapter has been written by paleoclimate scientists, who have studied the past climate to predict how it will change in the future. This is the first time this has happened. Their contributions help to put the climate of today in perspective. Cobb says that global surface temperatures are now at levels not seen since 100,000 years. "The rate at which the world has warmed up since 1970 is greater than any 50-year period over the past 2,000 years."
Global sea level rise is also confirmed by the report. Globally, sea level rose by 8 inches between 1901 and 2018. However, water rose more in certain places, such as some cities along the East Coast or Gulf Coast of the U.S.
The melting glaciers and Arctic ice are the main drivers of sea level rise. The report points out that even if all greenhouse gas emissions were stopped, sea levels will continue to rise for several decades.
Bob Kopp, who is one of the report's authors and director of Rutgers University's Institute of Earth, Ocean and Atmospheric Sciences, says that sea level changes through the middle of the century have largely been locked down. Those living along the coast will have to adapt to higher sea levels, regardless of what.
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Scientists agree that it is possible.
The new report, despite the dire predictions of a hotter Earth than it actually is, makes it clear that it is possible to reduce global warming. The Earth will remain more livable for the remainder of this century, and for many generations to come, if we reduce our emissions in this decade.
The big question that world leaders are asking is whether it's possible to achieve the goals set by the 2015 Paris Climate Agreement. The agreement aims to keep global warming below 2 degrees Celsius (3.6 degrees F) and, ideally, below 1.5 degrees Celsius (22.7 degrees Fahrenheit). Already, the Earth is about 1 degree Celsius warmer than it was in late 1800s.
Because they continue to rely on fossil fuels for electricity and transportation, most of the largest economies around the globe are not on track in meeting those temperature targets. This includes the U.S. which has seen its emissions decline very slowly in recent decades.
New research shows that it is possible to reach the Paris Agreement targets, but it becomes more difficult every day. Five scenarios were used by the authors to predict the future of global warming. These scenarios consider different levels of greenhouse gas emission, economic growth, and political collaboration. In the following two decades, Earth will reach 1.5 degrees Celsius (2.7 degree Fahrenheit) under all five scenarios.
"Is it possible to limit global warming at 1.5 degrees Celsius [Celsius]?" Maisa Rojas corradi, a University of Chile climate scientist and author of the report, says "Yes." "But, without immediate, large-scale and rapid reductions in all greenhouse gases, it will be impossible to limit global warming below 1.5 degrees."
According to the authors, the Earth could start cooling around the middle century if all countries cut their emissions significantly and permanently. However, countries that take longer to reduce emissions or fail to switch to cleaner energy sources could cause the Earth to heat by up to 4 degrees Celsius (7.2 degrees F).
Barrett, vice-chair of the IPCC, stated that while it was possible to prevent most of the worst impacts, it would require unprecedented and transformative change. "But the idea there is still a way forward, I believe, is something that should give us hope."
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While climate change is global, solutions to it are local.
This sixth edition of the IPCC climate science report is now available. It is also the first time that scientists have broken down their predictions and findings by region. This is a significant development because many countries depend on these reports to determine what the future holds for them and which policies are most effective.
The pace of sea level rising varies greatly depending on where you live. To make decisions about where and how to protect coastal cities, governments need to have regional information. This is also true for flooding and drought from rainstorms that disrupt agriculture and water supplies. In recent years, major cities like Cape Town, South Africa, and Chennai, India, have had difficulty maintaining their reservoirs.
Paola Arias (University of Antioquia, Colombia) says that it is important that the report provides regional information.
The U.S. does not rely on this specific report to help with adaptation. Instead, the federal government releases regular national climate assessments. The U.N. report provides important context for the Biden administration’s promise to reduce U.S. greenhouse gases emissions by half in the next decade.
Jane Lubchenco is the White House Office of Science and Technology Policy's deputy director for climate and environmental. She says that "the target that the Biden/Harris administration set earlier this year was the most ambitious ever in U.S. History." "This report tells us that we must be ambitious. It is likely that we need to be more ambitious.
It is unclear how the U.S. can achieve the goals it has set. The infrastructure package Congress is currently considering will include investments in cleaner electricity and public transit, as well as electric appliances and vehicles. Despite this, major economies like India and China are not expected to lower their emissions in the next decade.