The first thing people think about when hearing the words climate change is global warming and that the Earth’s surface temperature will continue its rapid warming over the next few years, expecting to continuously experience warmer temperatures throughout the year.
But how can we believe that the Earth is warming if we look at the extreme low temperatures in North Europe and North America at the moment?
Large areas of the Northern Hemisphere experienced one of the coldest springs on record, with the prediction in some regions, for searching for their Easter eggs in the snow. After very mild temperatures around Christmas and New Years the winter came late but hit with all it’s power and still dominates the North.
How can we reconcile these extreme cold temperatures with the idea of global warming?
Well, warmer temperatures primarily affect the very sensitive system of the oceans, causing water temperatures to raise, which in turn leads to the melting of the ice sheets. The Arctic sea ice in particular is melting rapidly with a mass loss of 80% in the last 30 years.
That sea ice loss, particularly with the record low we had in summer 2012, now is linked to the extreme weather experienced in the Northern Hemisphere.
This is possible because ice is mainly comprised of fresh water and with the high input of fresh water into the ocean due to melting, the whole system is shifting. This is not only due to the additional freshwater but also due to the heat transport from the ocean and atmosphere.
The Gulf Stream, which is very important for the Northern Hemisphere’s climate, is an Atlantic ocean current that transports warm Caribbean water to the high latitudes of the Northern Hemisphere and warms the surrounding atmosphere by releasing its heat.
With the change in ocean temperature and salinity the Gulf stream current will change and might shift direction, allowing colder Arctic air to move further south and stopping warm mid-latitude air moving far enough north.
The results are more extreme weather events for the Northern Hemisphere with heavy rain and snowfall, droughts and heat waves and more intense storms and flooding.