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2021 was a remarkable year for Earth’s climate » Yale Climate Connections


The close of another year provides an opportunity to assess what happened in the worlds of climate science and policy in 2021 and to gaze into a proverbial crystal ball to anticipate likely events in 2022.

This was a year full of climate-fueled extreme weather events, the publication of important new climate research and synthesis reports, and a crucial international climate negotiation. It ends with anticipation and uncertainty over whether the U.S. Congress will pass the country’s first-ever major climate change legislation.

2021 certainly did not lack for important climate events.

A hot year full of extreme weather

When the year comes to a close, 2021 will be the sixth- or seventh-hottest year on record and hotter than any year prior to 2015, despite a La Niña event’s having drawn cold water to the surface of the Pacific Ocean. La Niña years tend to be cooler than years with El Niño or neutral conditions in the Pacific. The year 2000 saw a La Niña event of similar strength to that in 2021, but 2021 was more than 0.4 degrees Celsius (0.75 degrees Fahrenheit) hotter than 2000. In short, 2021 was consistent with the long-term human-caused global warming trend of about 0.2°C (0.36°F) per decade.

Global average surface temperature change data from the NASA Goddard Institute for Space Studies divided into El Niño (red), La Niña (blue), and neutral (black) years, and years influenced by the short-term cooling effect of large volcanic eruptions (orange triangles).  Linear best fit trend lines are shown for El Niño, La Niña, and neutral years. (Graphic created by Dana Nuccitelli)

Extreme and often deadly weather events struck all around the world throughout 2021, but especially in the middle of the year marking the summer months in the northern hemisphere. From India to England to Russia to China to New Zealand to the U.S. to Indonesia to Uganda to Germany, it seemed as though every corner of the world was hit by extreme precipitation and flooding over the span of just a few months. A rapid attribution study of the German flood that resulted in more than 200 deaths found that global warming made the extremity of the event approximately five times more likely than in a hypothetical world without human-caused climate change.

Around the same time, extreme heat waves punished Japan, Ireland, Turkey, western North America, and England. The record-shattering extreme heatwave in the Pacific Northwest likely killed more than 1,000 people, and another rapid attribution study concluded that such extreme heat was “virtually impossible without human-caused climate change,” although the event was eerily similar to predictions made in a report from the Intergovernmental Panel on Climate Change (IPCC) had published a full two decades earlier.

Western North America, Siberia, and the Mediterranean region experienced intense droughts in mid-2021. With the combination of extreme hot and dry conditions, wildfires also ravaged these regions. California was hit by its second-worst wildfire season on record, behind only that of 2020. Siberia experienced its driest summer in 150 years and its worst wildfire season in memory. Summing it all up, CBS News meteorologist and climate specialist Jeff Berardelli described 2021 as having “the most extreme summer in memory.”

In August 2021, the IPCC published its Sixth Assessment Report, which concluded that humans are most likely responsible for 100% of the approximately 1.1°C (2°F) global warming over the past 150 years, and that climate change will continue to worsen extreme heat, droughts, wildfires, floods, and hurricanes. The Atlantic hurricane season came to a close at the end of November, and was described by meteorologist Jeff Masters as “bonkers” given  its extreme nature, including Hurricane Ida, which ranked as the fifth most costly weather disaster in world history. A December 2021 study by hurricane expert Kerry Emanuel of M.I.T. found that Atlantic hurricanes have become more powerful and more frequent over the past 150 years.

International climate negotiations and policy developments

The 26th Conference of Parties (COP) international climate negotiations convened in Glasgow in November 2021. At COP21 in Paris, countries had agreed in 2015 to update their individual climate targets five years later, but COP26 was delayed an extra year because of the COVID-19 pandemic. That postponement contributed to the widespread advance billings that COP26 indeed would be an extremely important event. And so it was.

The Glasgow negotiations yielded incremental but insufficient progress toward meeting the Paris targets. India pledged to reach net-zero emissions by 2070, and Nigeria by 2060, and 141 countries covering 91% of global forested area agreed to halt and reverse forest loss and land degradation by 2030. More than 450 financial institutions across 45 countries pledged $130 trillion of private capital to transition the global economy to net zero emissions by 2050; 103 countries responsible for close to half of global methane emissions pledged that by 2030 they will reduce those emissions by at least 30% from 2020 levels. The Glasgow climate pact agreement called upon all countries to “accelerate efforts towards the phase-down of unabated coal power and phase-out of inefficient fossil fuel subsidies.” That language was found vague and wanting by proponents of stronger action, but it nevertheless marked the first time a COP meeting specifically targeted coal and other fossil fuels.

The Glasgow agreement also “requests Parties to revisit and strengthen the 2030 targets in their nationally determined contributions [NDCs] as necessary to align with the Paris Agreement temperature goal by the end of 2022.” This request is unlikely to result in changes to the NDCs of countries like the U.S., which already has set an ambitious target (50% below 2005 emissions levels by 2030) roughly consistent with the Paris Climate Agreement. Reaching even that goal will pose stiff challenges on Capitol Hill, likely making more ambitious targets unachievable. The language may apply more to countries like China, whose NDC only aims to peak emissions before 2030 and achieve carbon neutrality before 2060 – targets that the country is already on track to meet without substantial additional policy efforts.

In the U.S. climate policy world, the infrastructure bill signed by President Biden on November 15th  contains some significant climate-relevant investments, including a $66 billion investment for rail; $65 billion to improve the electricity grid; $44 billion for public transit; and $7.5 billion for electric vehicle charging stations. Four days later, the House of Representatives passed a budget reconciliation package with about $555 billion in climate-related investments including $163 billion in clean electricity tax incentives; $135 billion for home efficiency and electrification; $30 billion to create a Civilian Climate Corps; and $20 billion for electric vehicle tax incentives. That package is now under review in the Senate, where Majority Leader Chuck Schumer (D-NY) has expressed his goal to pass its version by Christmas, to then be sent back to the House for approval. Once past those not insubstantial milestones, a bill could be forwarded to the President for signature and enactment in early 2022.

Analyses by various energy policy modeling groups – including Energy Innovation, Princeton ZERO Lab, Rhodium Group, and Resources for the Future – estimate that the climate provisions in the infrastructure and House-passed reconciliation packages are sufficient to reduce U.S. greenhouse gas emissions to approximately 35-45% below 2005 levels by 2030; shy of the country’s 50% by 2030 NDC. Several senators are pressing to add a price on carbon pollution to the reconciliation package, which would likely add enough greenhouse gas emissions cuts to meet the U.S. NDC, but it remains to be seen whether West Virginia Democratic Senator Joe Manchin will be convinced to offer the key needed 50th vote in support of such a measure. If he does, Vice President Harris would be in line to break the 50-50 tie, with all Republican Senators voting against the legislation.

What else is coming in 2022?

Heading into 2022, models project that the current La Niña event will subside and be replaced by neutral conditions in the Pacific. The National Oceanic and Atmospheric Administration predicts that the coming winter months will be relatively hot across much of the U.S., particularly in the southern states, and that the persistent drought in the southwestern states will continue. These conditions could lead to yet another dangerous western wildfire season in the summer and fall months.

The body of research into potential links between the rapid warming and sea ice decline in the Arctic and hot and dry conditions in the southwestern U.S., including a new Nature Communications study on the subject published in October 2021, may continue to develop in 2022. Some nations will strengthen their NDCs for COP27 in Egypt, possibly including China. And the U.S. will hold midterm elections in which the Republican Party may wrest control of one or both chambers of Congress from the Democrats, which would likely once again grind the gears of domestic climate policy to a halt.

In short, 2022 will be another consequential year for Earth’s climate, as likely will be every year henceforth on our heated planet.





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