Understanding Abrupt Climate Change in the Late Quaternary

by R.S. Bradley & H.F. Diaz, Nov18,  2021 in Eos

Between about 75,000 and 10,000 years ago, there was a series of sudden and dramatic changes in rainfall patterns in tropical regions likely triggered by changes in ocean water circulation. A recent article in Reviews of Geophysics examines the evidence of these “Tropical Hydroclimatic Events” and explores the potential causes. Here, one of the authors explains more about these abrupt climate change events of the past and suggests how it can inform our understanding of potential future climate change.

What are “Tropical Hydroclimatic Events” (THEs)? When and where did they occur?

When we look back at past climate variations in continental regions of the Tropics and sub-Tropics (~30ºN-30ºS), it is abundantly clear that there were times when climate abruptly changed, causing some areas that were formerly wet to become quite dry, and areas that were formerly dry to become much wetter, disrupting plant and animal communities, as well as people living in the region. We call those changes “Tropical Hydroclimatic Events (THEs).” The changes affected vast areas (and lasted for centuries in some cases_ before the climate shifted back to the former conditions. There were at least half a dozen of these THEs between about 10,000 and 75,000 years ago.

Deloitte: Climate change will cost $178T by 2070

by M. Cohn, May 23, 2022 in AccountingToday

Climate change could cost the global economy $178 trillion over the next 50 years, or a 7.6% cut to global gross domestic product in the year 2070 alone, according to estimates from Deloitte.

A report released Monday by the Big Four firm in conjunction with the World Economic Forum’s annual meeting in Davos, Switzerland, also acknowledged the human costs of the climate crisis. If global warming reaches approximately 3 degrees Celsius by that point, the toll on human lives could be significant, disproportionately affecting the most vulnerable and leading to loss of productivity and employment, food and water scarcity, declining health and well-being, and ushering in an overall lower standard of living across the world.

Bringing order to the chaos of sea level projections

by Royal Netherlands Institute for Sea Research, May 18, 2022 in ScienceDaily

In their effort to provide decisionmakers with insight into the consequences of climate change, climate researchers at NIOZ, Deltares and UU are bringing order to the large amount of sea level projections, translating climate models to expected sea level rise. Their new overview study was published in the scientific journal Earth’s Future. “These results offer tools for decision making on the shorter and longer term.”

Aimée Slangen is a climate scientist at NIOZ and co-author of the IPCC climate report. Together with climate adaptation experts Marjolijn Haasnoot and Gundula Winter from Deltares and Utrecht University, both also IPCC authors, Slangen investigated the similarities and differences between the many sea level projections published in recent years.

Eight families of projections

“We found that the set of more than 80 different projections can be reduced to eight ‘families’,” says Slangen. “Within each of the families of projections that we identified, researchers have often used similar data, but they have for instance used different model approaches. As a result, every new publication resulted in different amounts of projected sea level rise, depending on whether the publication focused on the shorter term or the longer term, or depending on the models used to estimate the processes causing a potentially large contribution of accelerated melting of the Antarctic ice sheet.”

These details are interesting for scientists, but make it more difficult for users to maintain overview. Slangen: “This can be an issue when you have to decide as a government what you are going to do to protect your coasts from rising sea levels. Decision makers can’t adjust their policies with every new publication.”

Half a meter rise before the end of the century

The researchers hope to dispel this doubt, as all families paint a similar picture for the first 50 cm of sea level rise. Slangen: “We will see the first half-meter rise before the end of this century, even if we start reducing greenhouse gas emissions on a large scale. For this period, it therefore makes little difference which family you use for sea level projections.”

According to adaptation expert Haasnoot, this therefore means that we can already start adapting to the consequences of sea level rise now. “Those who have to make the climate-proof decisions can already get started. However, it is important to take into account the uncertainty of the future. If you plan cleverly, you make sure that what you are doing now for a half meter sea level rise can be adjusted later for one meter. That will save a lot of money and effort.”

Models and emission scenarios