04/10/2016 12:15 BST | Updated 05/10/2017 06:12 BST

Oceans, Negotiations And Boundaries: Why We Must Keep Global Warming To 1.5 Degrees

Reuters Photographer / Reuters

September 2016 will be remembered as the month when carbon dioxide levels failed to drop below 400 parts per million. Scientists claim that it is unlikely that levels will ever dip below this threshold again, and that we are headed for a future on an unstable, unpredictable planet. This latest news is yet another clear signal to world leaders that concrete and practical action must be taken to combat global warming.

Steps forward have already been made. The signing of the Paris Agreement at the United Nations Conference of Parties (COP) in December 2015 was an historic moment. The agreement, signed by 175 countries, outlined goals 'to pursue efforts to limit the temperature increase to 1.5 degrees' above pre-industrial levels. This was a leap in the right direction in the fight against global warming and environmental injustices. But there were also omissions, such as a failure to mention 'fossil fuels' even once, or to legally bind countries to the measures.

Why is it so crucial for countries to stick to the Agreement? What is at stake not only in political arenas, but in the real world, if temperatures were to rise above 1.5 degrees?

Participants at Oxford University's 1.5 Degrees conference in September agreed that it is hard to underestimate the negative consequences of warming above 1.5 degrees. Professor Michael Oppenheimer, member of the Intergovernmental Panel on Climate Change (IPCC), stated that many models nevertheless currently underestimate the scale of future damage, and that 'the uncertainty here is huge'.

But we can already see the visible effects of warming. Nowhere is this perhaps more strikingly obvious than in the Arctic. Measurements taken by the US National Snow and Ice Data Centre (NSIDC) show that this year's minimum sea ice cover is one of the three lowest on record. The ice is disappearing. Marine temperatures and sea levels are rising. This is problematic not just locally, but on a global scale, in ways which go far beneath the surface of the ocean and beyond the melting ice-sheets. The marine environment is indeed a central component to understanding why warming must be limited.

Habitats, species, and those who depend upon the oceans for their livelihoods are already suffering. As fish species migrate away from their usual territories due to rising temperatures, fishermen in South East Asia in particular are likely to suffer smaller catches, and many regional marine ecosystems will crumble as the natural food chain is disrupted. Closer to home in the UK, haddock in the North Sea are growing to smaller sizes and producing fewer eggs, which has a negative impact on UK fisheries and the food chains of which they are a part. Furthermore, the Great Barrier Reef recently suffered extensive coral bleaching due to high temperatures. Although coral reefs can recover in cooler spells, in a future where water temperatures are constantly rising, this fact offers little consolation.

Looking to the future, atolls and island states such as the Maldives and the Marshall Islands are at risk of being swallowed beneath the waves if current rates of warming continue. We could see huge forced migration and the loss of entire nations. Even if global air temperatures cease to increase at their current rate, sea levels and water temperatures will continue to rise as the oceans will release stored heat for many centuries. Because of this long-lasting feedback, it is even more crucial to limit warming now. As Laurence Tubiana, French Ambassador for climate change negotiations, stated in Oxford, 'the best case for justice is for us to do what we have to do - limit warming to 1.5 degrees.'

We are on the way: on September 21st 2016, 31 more governments ratified the Paris Agreement, meaning that with 60 countries on board at that point, the Agreement sped closer to entering into force. 55 countries accounting for at least 55% of global emissions must have ratified for the process to take effect. India was the latest country to join, on October 2nd, bringing the percentage of emissions accounted for to 51.89%. This fast-track ratification bodes well for discussions at the upcoming UN climate conference (COP22) in Marrakech.

There are, therefore, high hopes for Marrakech. Political decisions made in the UNFCCC-managed spaces of COP22 must be legally binding. Discussions must consider not only the economic and political consequences of a 1.5 degrees (or greater) rise in temperatures, but the interconnected lives, livelihoods and ecosystems at stake. Governments must make commitments to divestment, to renewable energy, and to reducing the output of greenhouse gases from transport and industry. We must strive, in every possible way, to keep warming at, or below, 1.5 degrees.