Just keep swimming swimming swimming

"They keep saying that sea levels are rising an' all this. It's nowt to do with the icebergs melting, it's because there's too many fish in it. Get rid of some of the fish and the water will drop. Simple. Basic science" - Karl Pilkington

Figure 1: Cartoon of sea ice melting - Source: Nate Fakes 

If only science was as easy as Karl said it is, I wouldn't be permanently tired (My favourite thing about being at UCL) and everyone would graduate with 1st class honours and a bright future ahead of them. Unfortunately, that isn't case! 

Anyone who knows anything about climate change will know that global sea levels (GSL) are rising at accelerating rates. But they may not know the Pacific islands are the most affected nations in the world by climate change and are considered amongst the most vulnerable to sea level rise (SLR). In my previous blog post, I wrote about the effects of different warming scenarios. In the this blog, I will talk about the actual causes of SLR.

Why are the Pacific islands at such risk?

The pacific nations are under extreme threat due to their low lying nature, particularly the atolls of Micronesia. The islands in Melanesia and Polynesia tend to be higher above sea level due to their volcanic state. The lowest lying islands are Kiribati and Tuvalu, with only 1/3 of the land being < 2 meters above sea level and about 8% being 3 meters above sea level respectively.  The highest elevation Pacific islands are those of the Solomon Islands, many of which are 500 meters in elevation. To put this into perspective, London is 35 meters above sea level, so luckily, I'm safe for the time being.

Figure 2: Map of Pacific islands - Source: The end of the Pacific? Effects of sea level rise on Pacific Island Livelihoods

Figure 3: Graphic showing the average sea level rise experienced by a number of Pacific islands (FSM = Federate states of Micronesia & PNG = Papua New Guinea) - Source: Small Islands adrift 

Recent papers looking at SLR based on different climate change projections, suggest by 2100, the worst-case scenario will display sea level increase by 132cm. Despite this seeming large, numerous other papers make this figure seem quite lowly, by suggesting SLR may be between 150 - 184cm. This would see the Pacific islands under water and places like New York and Mumbai facing extreme flooding.

Causes of sea level rise

Within the past century, the dramatic increase in fossil fuel emissions and other human activities have released a gargantuan amount of heat trapping greenhouse gases E.g. CO₂ into the atmosphere. Consequently, the atmospheric concentration of CO₂ has reached 402ppm, an increase of 120ppm from three centuries ago. These emitted gases absorb the suns radiation, causing the Earth's temperature to rise, concurrently reemitting the radiation, allowing the additional radiation to be absorbed by the ocean. SLR can be attributed to three main issues. 

 Figure 4: Interactive graphic displaying the changes in global carbon dioxide concentration since 1980

Ice loss from Greenland and Antarctica

Greenland  is a gigantic glacier and is considered one of the largest contributors to GSL rise. A number of different causes, such as increased surface melting,  decreasing ice albedo and  increasing surface air temperature have all contributed to the staggering rate of melt in Greenland.

Video 1: Time lapse of the change in ice mass in Greenland since 2003

Temperatures in Greenland have increased by up to 5^°c in recent years, drastically increasing the glacier's propensity to melt. This increased tendency to melt has created more run off, subsequently causing increased sliding at the base of glacier allowing more calving into the ocean.

Video 2: Interactive 360 degree video showing the extent of ice melt in Greenland and explaining the reasoning behind its extreme melt

Studies show that the Greenland melt is accelerating at unprecedented rates, growing from 0.09mm/yr  between 1992-2001 to 0.59mm/yr between 2002 and 2011. This astonishing melt rate is estimated to add 200-300 gigatons of water per year to the ocean (1 gigaton = 264 billion gallons & 500,000 gallons = Olympic size swimming pool!). To contextualise this, melting 365 gigatons of ice would add 1 millimetre of water to GSL.

Video 3: Snippet from the document "Chasing ice" showing the worlds biggest glacier calving event

Antarctica is also quickly adding to GSL, with estimates suggesting it's contributed 0.08mm per year between 1992 and 2001 compared to 0.40mm per year between 2002 and 2011. This has added somewhere in the range of 71-141 gigatons of water per year. 

Melting glaciers and polar ice caps

Glaciers and polar ice caps have contributed between 2.6-2.9mm/yr, for the past 20 years to GSL, placing these small ice masses in the top 3 greatest contributors to SLR. The largest losses are seen in Arctic Canada, Alaska and coastal Greenland, but mountain ranges such as the Andes and Himalayas also add considerably.

Figure 5: Comparison between the contribution of glaciers, Greenland and Antarctica to sea level change  

Mountainous regions have been experiencing intense glacier retreat since the 1850's, producing countless gallons of meltwater, adding to SLR. A prime example of this Glacier National Park in the USA, which could potentially become Glacierless National Park by 2050.

Video 4: Talking about the loss of glacier ice in Glacier National Park and how Glacier's are tracked

The Arctic is thought to have the greatest number of glaciers in the world, amounting to an area of 277,000km² (excluding the main ice sheet).  However a reduction in the albedo feedback loop has caused the arctic to warm at twice the global average, causing glaciers and sea ice to decline. Previously, I wrote about the average global warming experienced in 2016, with figure 5 agreeing and reiterating the severity of warming seen in the arctic. 

Figure 6: Average air temperature between 2000 to 2014 in the Arctic - Source: Nature

Thermosteric expansion

The earth primarily warms due to the accumulation of heat trapping greenhouse gases, yet approximately 90% of this heat is absorbed by the world's oceans, as they act as major anthropogenic sink for climate change. 

Video 5: Explains the science behind thermal expansion and the resulting effects of this added heat

The estimated rate of thermal expansion from 1971 to 2010 are between 4 to 8mm/yr. But most estimates are restricted to the upper section of the ocean between 0-2000m depth due to the ARGO system. Consequently, deep ocean warming is still poorly understood. However studies have begun to show evidence of deep sea warming in the South Atlantic and Pacific.

At the heart of these issues is global warming; producing a combination of problems which dramatically increase the vulnerability of the Pacific Islands, putting them in grave danger of disappearing. To combat this, I believe the world’s largest emitters should take responsibility, by making steps towards reducing their emissions. Hopefully at the upcoming COP23 this will happen! 

Hope everyone has a good week!
Wells

What is more important, the question or the answer?

"The climate bill has finally come due. Who will pay? Right now, it is being paid by the smallest and most vulnerable" - Baron Waqa, Ex-President of Nauru

Climate change has many sceptics across the planet, but one aspect of the issue, which is undeniably true, is global warming. Over the past few years, an amounting pile of evidence has been generated proving the earth is gradually warming.

Figure 1: Cartoon questioning when the world will have a legally binding climate change agreement - Source: KAL

The Paris Agreement

On the 22nd of April 2016 (Which funnily enough happens to be my birthday), a massive step was finally taken towards reducing global warming and its obvious implications, known as the Paris Agreement. It is an UN sanctioned agreement dealing with greenhouse gas emissions, mitigation, adaptation and finance of climate change.

Figure 2: Collection of newspaper headlines highlighting the urgency of vulnerable nations

One major aspects of the accord, revolved around the decision to aspire to reduce global warming to 1.5°^c or 2.0°^c, with the latter being the final agreement. This decision caused great controversy and uproar amongst the Alliance of Small Island States (AOSIS), with them dubbing anything below 2.0°^c “wholly inadequate”, further vexing the up-hill struggle these nations face. AOSIS have been long term advocates of  "1.5 To Stay Alive" movement as it represents the level of global warming beyond which many of AOSIS nations will be vulnerable and overwhelmed by severe climate impacts.

Figure 3: GIF displaying how global temperatures have increased monthly from 1850-2016, culminating with 2016 being the hottest year in history.

Many scientists question the aggressiveness and ambition of the Paris accord, as forecasted global temperatures don't show a prosperous future for many nations.  Figure 3 shows between January and March 2016, the average global temperature change was 1.48°^c almost meeting the global warming threshold of 1.5°^c, providing another stark reminder that we are much closer to 1.5°c threshold than perhaps many people think.

Figure 4: Schematic showing how far we are from the 1.5°^c threshold on different paths - Source (Climate Central)

Now you may question what is the difference between 1.5°^c and 2.0°^c? Let me explain..

While our dearest mother earth is extremely resilient, it is also very fragile. The small increase of 0.5°^c in global mean temperature would have a gargantuan effect on small island states, causing a substantial decrease in water availability, an increase in regional dry spells and severe degradation to virtually all tropical coral reefs due to temperature induced bleaching. Tropical regions would also experience a considerable decrease in crop yields and sea level rise would be unprecedented, with a 2.0°^c scenario showing a predicted sea level rise of 30% greater than a 1.5°^c scenario.

In my own opinion, I believe the Paris agreement was a true landmark climate accord, exceeding the expectations of many, whilst recognising crucial long term climate goals, kick-starting renewed climate bureaucracy and inspiring a generation of climate activists. My following blog posts will talk about the causes of global sea level rise.

As Waqa said, the smallest and most vulnerable have been hit hardest, yet they have shown great resolve in face of adversity. Through the #HaveYourSei campaign, Pacific islanders show how a torpid approach to climate change exacerbates the threat. I feel it's imperative we support the Pacific climate warriors by signing the declaration!

Video 1: Pacific Islanders explaining the #HaveYourSei and why they need strong climate action!

The Pacific have asked the questions; they are now waiting for the world to answer. 

#HaveYourSei

Wells