![]() ![]() Technologies that can capture already emitted carbon dioxide have many proponents, but they must not come at the expense of efforts to turn off emission sources. It is impossible to overstate the urgency with which we need to reduce greenhouse gas emissions. The scale of the oceanic contribution to storing heat means any small change to how this has operated over the past millennia may have very large impacts. It might be the world's biggest ocean, but the mighty Pacific is in peril While El Niño conditions can bring marine heatwaves to some areas of the Pacific, the oceans around Aotearoa New Zealand, especially to the south, are already experiencing nearly constant marine heatwaves. We have to disentangle these to understand long-term changes. The Pacific is so large it has its own internal cycles, such as the El Niño Southern Oscillation ( ENSO). Aotearoa New Zealand sits in the southwest corner of the Pacific Ocean, which covers about a third of the globe’s surface. Ben Noll/NIWA/NOAAĭespite the connected ocean, the individual basins have their own characteristics and contributions to climate. The stippled areas mark marine heatwave conditions. Surface temperatures around Aotearoa NEW Zealand for May 1, 2023. Recently, the Drake Passage has been shown to be even more of a mixing hotspot than previously thought. While we can predict some of this mixing, the ocean is full of surprises. This is because very little of the ocean’s mixing has been observed directly. It is beyond even our most powerful climate simulators to model exactly how the heat is spread, making predictions less certain.Įven if our models could work at very big and very small scales at the same time, they would have few data for validation. The difficulty for researchers determining how best to respond is that the processes that move and mix this heat operate over very small scales. This in turn changes how the upper ocean absorbs carbon dioxide. Heating the ocean surface makes the upper reaches more stable. One of the unknowns of ocean warming is how the oceans will adjust and store all the heat. ![]() Torrents of Antarctic meltwater are slowing the currents that drive our vital ocean 'overturning' – and threaten its collapse These freezing coastal waters of Antarctica are a crucial engine room for global currents that convey energy around the planet – and this ocean transport mechanism is now changing. With less sea ice, there is less cold, salty, oxygenated water sinking to the deep ocean. ![]() This is because polar sea ice acts as a connector between the atmosphere, the surface of the ocean and deeper waters. Author provided, CC BY-ND The global ocean heat transport What satellites measure can differ from temperatures just below the surface or in the deeper ocean. ![]()
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