Warmer summers in the far Northern Hemisphere are disrupting weather patterns and triggering more severe winter weather in the United States and Europe, a team of scientists say, in a finding that could improve long-range weather forecasts. Blizzards and extreme cold temperatures in the winters of 2009/10 and 2010/11 caused widespread travel chaos in parts of Europe and the United States, leading some to question whether global warming was real. Judah Cohen, lead author of a study published on Friday in the journal Environmental Research Letters, and his team found there was a clear trend of strong warming in the Arctic from July to September. Existing predictions would also expect a warming trend during winter as well. But Cohen and his team found this was not the case for some regions, in a counter-intuitive finding that reveals more about the complexity of the world’s climate system than any flaws in the science of global warming. “For the last two decades, large-scale cooling trends have existed instead across large stretches of eastern North America and northern Eurasia. We argue that this unforeseen trend is probably not due to internal variability alone,” the scientists say in the study.

Atmospheric levels of methane, 20 times more powerful than carbon dioxide (CO2) at trapping heat, stayed steady for two decades to 2006 on wider fertilizer use to grow rice or a surge in natural gas demand, according to two separate studies in the journal Nature. Climate researcher Fuu Ming Kai from the Massachusetts Institute of Technology’s Singapore research center said in one study that methane output from rice fields in the Northern Hemisphere dropped during the period as fertilizers replaced manure and because of reduced water use. In the second study, Murat Aydin at the University of California, Irvine, concluded that a drop in methane emissions from more efficient burning of fossil fuels and a surge in natural gas demand.

Scientists are outfitting elephant seals and self-propelled water gliders with monitoring equipment to unlock the oceans’ secrets and boost understanding of the impacts of climate change. Oceans regulate the world’s climate by soaking up heat and shifting it around the globe. They also absorb huge amounts of planet-warming carbon dioxide, acting as a brake on the pace of climate change. But scientists say they need to ramp up a global monitoring network, with the Southern Ocean between Australia and Antarctica playing a key role. The Southern Ocean is a major “sink” of mankind’s carbon emissions and an engine of the world’s climate.