Two months is never an indicator of climate. Climate, by definition is ‘the prevailing weather in a location over a prolonged period’. However, there have been some rather alarming developments in the Arctic regions over the past couple of months.
Last month was on average 1.35°c warmer across the globe than the 1950-1981 average for February. However, this warming was concentrated predominantly in the Arctic regions, where temperatures were over 10°c warmer than the 1950-1981 average. That is an incredible temperature extreme, especially considering that when discussing severe climate change we talk about at the most 3-4°c changes in temperatures over decades, even centuries, so to see temperature spikes of this magnitude is extraordinary. The extent to which this high global average is related to the strong El Niño effect that is currently influencing much of the tropical Pacific Ocean is relatively unknown, but even considering this year’s strong El Niño, the temperatures being witnessed in much of the Arctic and large areas of Russia and Siberia are worrying. The localised impact of El Niño can clearly be seen on the map in the Pacific Ocean west of South America, but it is generally not known how much of a role it has played in particularly the extreme warming seen in the Arctic regions and continental Russia.
Why are these temperatures a concern?
Although this may seem like a rather obvious statement to be making, it is crucial that there is a universal understanding of why a rapidly warming Arctic is dangerous regarding global warming. The Arctic is like an end-member in the climate system. It is located at the Northern extreme of our planet and therefore experiences some of the coldest temperatures and levels of solar radiation on Earth.
It also plays a key role in several key climate controls on Earth today. First is sea ice, and this is not so much regarding the melting of ice increasing sea level, but regarding the change in surface colour that is produced. As levels of sea ice in the Arctic decrease, more and more of the ocean surface is exposed to incoming solar radiation. The ocean surface is much darker than the white sea ice and therefore absorbs more solar radiation, rather than reflecting it back to space. In effect this means that more energy and therefore heat is absorbed into the Earth system, increasing the warming effect we are currently witnessing. This process is known as a feedback loop, whereby initial warming produces a change that amplifies this warming. Specifically, this feedback loop is known as the albedo feedback loop, albedo meaning surface reflectivity ratio.
Another key climate control that is located in the Arctic, and particularly in areas of Siberia that experienced over 10°c warmer temperatures in January and February is methane permafrost stores. This is frozen stores of methane gas that are permanently frozen due to the cold temperatures in these high latitude areas of the world. As the climate warms, permafrost begins to thaw and as this happens methane gas will begin to outgas into the atmosphere. This is a great worry to scientists and world bodies because methane is a much more effective greenhouse gas than carbon dioxide (however it does not remain in the atmosphere as long as CO2, hence the greater attention on CO2), therefore its feedback amplification of global warming would likely be substantial.
The final major climatic control that the Arctic influences upon is ocean circulation. Different parts of the Earth receive different levels of solar radiation and heat. For example, the equators receive the highest intensity of solar radiation and it is year-long, hence why their seasons are negligible. Contrastingly, at the poles seasons are extremely pronounced with periods of 24-hour darkness 24-hour spearheading the seasons. This is all a consequence of the Earth being at an angle to the sun, and the end result is that the equator receives much more solar radiation and heat than the poles. The Earth is governed by physical and chemical laws, so therefore wishes to reach an ‘equilibrium’, where heat is evenly distributed across the planet. In reality it will never reach this equilibrium, but one of the ways it tries to achieve that is a global network of ocean circulation.
This network is known as the Thermohaline ocean circulation because it is dependent upon differences in temperature and salinity of seawater. Cold, saline water is denser than most sea water and will therefore sink and flow south towards the warmer equatorial regions. Conversely, warm, less saline water will rise and flow towards the cooler polar regions, and this is one of the reasons that the UK is on average milder than its latitude would dictate (Glasgow is roughly at the same latitude as Moscow!). How this links back to a rapidly warming Arctic is that warmer Arctic oceans and increased melt from the Greenland ice sheets will weaken the differences in density that are crucial to ocean circulation. In an extreme scenario the mechanism could be weakened enough to produce total shut down of this branch of ocean circulation, however current estimates by the Intergovernmental Panel on Climate Change (IPCC) deem this unlikely before 2100.
There is some rather heavy science in the paragraphs above, which at times is not particularly helpful in understanding these issues, and the severity of the threats they pose. The important messages to take from these extreme temperature readings in the Arctic is that it is concerning, but it is not an indicator of climate yet and has not lasted for long enough to produce a severe warming effect. We need to evaluate the long term evolution of this trend and particularly consider it after the current strong El Niño effect has subsided.
Whatever the outcome of this, severe warming in the Arctic is always concerning because of its crucial role in many climate feedback loops. Below is a latitude map from the south pole (left) to north pole (right) showing the average warming in each respected latitudinal zone. Compare this to the warming trends shown on many of the IPCC maps produced, and the trend between recent observed warming this year and the IPCC’s forecasts for the most extreme levels of warming to be in the Arctic is a worrying one.
NASA tells us the zonal mean temperatures for the first couple of months of this year, plotted against latitude. Clearly the extremely high temperature values are polarised towards the Arctic regions (75°+) and there is a general trend of warming in the northern hemisphere (0-90°). This is to be expected because of the greater proportion of landmass in the northern hemisphere and the cooling effect of Antarctica in the southern hemisphere. Consider this Arctic bias of warming when viewing some of the IPCC temperature projection maps under different emission scenarios for 2100. Note the right hand graph, which is the most severe emission scenario, very much bares resemblance to that of the temperature map shown at the start of this article.
Considering all of the above, what is an appropriate response to these recent developments? World leaders need to sit up and take notice of these observations, and start considering climate change as a serious threat to their respective nations and the world. There has been a chronic failure by politicians and business to recognise and address the current danger posed to the world community and economy by dangerous levels of climate change. The risks need to be translated into language that resonates with politicians, economists and the public alike, otherwise we are all going to sleep-walk straight into a catastrophe.
For individuals, watch this space. The current trend is relatively short lived and may be linked to the very strong El Niño effect currently in action. Nonetheless, these temperatures are still shocking and beyond what many scientists ever anticipated seeing this decade. Should they persist for the coming months and years there is the danger that Earth’s climate could be forced towards dangerous levels of exponential warming, which we would have very little control over. Considering this, let us hope that those temperatures start to return to more traditional levels sooner rather than later.