Luminous ‘mother-of-pearl’ clouds explain why climate models miss so much Arctic and Antarctic warming

Katrin Meissner, UNSW Sydney; Deepashree Dutta, University of Cambridge, and Martin Jucker, UNSW Sydney Our planet has warmed by about 1.2°C since 1850. But this warming is not uniform. Warming at the poles, especially the Arctic, has been three to four times faster than the rest of the globe. It’s a phenomenon known as “polar amplification”. Climate models simulate this effect, but when tested against the past 40 years of warming, these models fall short. The situation is even worse when it comes to modelling past climates with very high levels of greenhouse gases. This is a problem because these are the same models used to project into the future and forecast how the climate will change. They are likely to underestimate what will happen later this century, including risks such as ice sheet melting or permafrost thawing. In our new research published today in Nature Geoscience we used a high-resolution model of the atmosphere that includes the stratosphere. We found a special type of cloud appears over polar regions when greenhouse gas concentrations are very high. The role of this type of cloud has been overlooked so far. This is one of the reasons why our models are too cold at the poles. Polar Stratospheric Clouds over Norway (Night Lights Films - Adrien Mauduit) Back to the future Looking...

Read More........→November 08, 2023

Polar bears may struggle to produce milk for their cubs as climate change melts sea ice

During their time onshore, polar bear mothers may risk their survival by continuing to nurse when food is not available. (Shutterstock) Louise Archer, University of TorontoWhen sea ice melts, polar bears must move onto land for several months without access to food. This fasting period is challenging for all bears, but particularly for polar bear mothers who are nursing cubs. Our research, published in Marine Ecology Progress Series, found that polar bear lactation is negatively affected by increased time spent on land when sea ice melts. Impaired lactation has likely played a role in the recent decline of several polar bear populations. This research also indicates how polar bear families might be impacted in the future by continued sea-ice loss caused by climate warming. Challenges of rearing cubs While sea ice might appear as a vast and perhaps vacant ecosystem, the frozen Arctic waters provide an essential platform for polar bears to hunt energy-rich seals — the bread and butter of their diet. Sea ice is a dynamic environment that can vary through time and in different regions of the Arctic. Polar bears in Canada’s western Hudson Bay area experience seasonal sea ice, which melts in the warmer summer months, forcing the polar bears to move onto land until cooler winter temperatures cause the sea ice to refreeze.While...

Read More........→October 09, 2023