Climate Change: What Happens after 2100?

2011•11•16 Gregory Trencher University of Tokyo

We all know that the carbon legacy of our fossil fuel-based lifestyles is bequeathing a climate crisis to billions of people into the future. But when we say “future”, just how far should we be thinking ahead? As far as 2050? 2100? Or a little bit further, maybe as far as 2500 and beyond?

You may have already noticed that future climate projections used by the international scientific and political communities generally go only as far as the year 2100. The simple reason for this is that it is impossible to predict with any degree of accuracy just how much greenhouse gases are going to be released in the next few centuries, and just how much this is going to affect the climate.

But don’t be fooled. This does not mean that climate change will cease to be a problem in the years lying beyond the upper reach of our most cited climate forecasts. The shocking truth is that climate change has only just begun. Regardless of future emission trends, the CO2 footprint from our brief passage on Earth is going to remain in the climate system and impact the well-being of all terrestrial life forms for what could almost be considered an eternity.

The majority of C02 emitted from burning a single tonne of coal or oil today will be absorbed over a few centuries by the oceans and vegetation, the remaining 25% will still be affecting the climate in 1,000 years.

According to scientist David Archer, whose research is often featured in the renowned Nature magazine, the C02 that we are emitting from fossil fuels today will still be affecting the climate in many millenia from now. His conclusion is that even though the majority of C02 emitted from burning a single tonne of coal or oil today will be absorbed over a few centuries by the oceans and vegetation, approximately 25% of it will still be lingering in the atmosphere in 1,000 years, and 10% still remaining and impacting the climate in 100,000 years time.

It will then require thousands and thousands more years for its complete absorption through the natural climate cycle. As Archer puts it, “the climatic impacts of releasing fossil fuel C02 to the atmosphere will last longer than Stonehenge, longer than time capsules, longer than nuclear waste”.

The Copenhagen Diagnosis

Some of this future devastation is briefly discussed in the recently updated Copenhagen Diagnosis — a report authored by 26 leading climate scientists with the aim of updating the world on findings since the publication of the IPCC Fourth Assessment Report in 2007. According to this Copenhagen Diagnosis, regardless of when a peak in global emissions finally occurs, the global temperature cannot be expected to stop rising until several centuries later, due to the extremely long life cycle of C02.

The carbon that we are releasing into the atmosphere today is in the process of ‘programming’ a potential 2-5 metres of sea level rise by around the year 2300.

But that’s not all. The report also states that “even a thousand years after reaching a zero-emission society, temperatures will remain elevated, likely cooling down by only a few tenths of a degree below their peak values.”

In other words, whatever the mitigation efforts of future civilisations, climate change is here to stay. Only after this extremely long period of forced warming — far more than the history of modern civilisation since the Scientific Revolution — will climate change slowly begin to ‘reverse’ and the planet will at last embark on a cooling trajectory, the report explains.

But long before this ever happens, humanity must prepare itself for an inland retreat and a constant battle against rising seawater that will continue for hundreds and hundreds of years into the future. The phenomenon of sea level rise resulting from thermal expansion (sea water expands as it warms) and melting ice sheets in Greenland and Antarctica is the perfect illustration of climate inertia in action.

As may be seen from the graph below, showing estimates from three different models, it takes several centuries for the oceans to fully respond to a warmer climate and altered carbon balance. As a result, the carbon that we are releasing into the atmosphere today is in the process of ‘programming’ a potential 2-5 metres of sea level rise by around the year 2300.

What’s more, the authors of the Copenhagen Diagnosis warn that sea level rise will continue for many centuries after the eventual stabilisation of global temperature (and therefore beyond the upper limit of this graph too). This is no doubt going to have a devastating impact upon future cities, towns, agricultural areas and freshwater resources located near coastal regions. (The Centre for Remote Sensing of Ice Sheets has some detailed images available of the areas of the globe most threatened by sea level rise.)

Small decisions, huge consequences

With this geological mayhem scheduled to take place over the next several thousand years, the decisions that we are making (read: not making) in the present take on a new light. Clearly we need to expand the time scale with which we assess the full implications of the climate crisis beyond the current century. Once humans turn up the planetary thermostat by 2°C (the goal to which the international community is committed at present, albeit very optimistically), there will be no turning it back, save a trend towards planet-altering geo-engineering.

Instead, the temperature control will be locked in and all life forms on Earth will be pressured to adapt for thousands of years. The climate change-driven ecological destruction that we are witnessing today — immeasurable loss of human life, plant and animal species caused by natural disasters such as floods, droughts, wildfires and heat waves, the disappearance of vast snow caps, glaciers and almost half of the Arctic — is the result of a mere 0.8°C rise in average temperature since 1800. We can only imagine what a further 1.2°C rise before 2100 will mean for the Earth’s already vulnerable ecosystems and at-climate-risk communities.

Future ethics

The planet is the ultimate ‘global commons’. It belongs to neither a particular individual nor a particular nation. Nor does it belong to a single generation such as us, our children or our grandchildren. Instead, it belongs to all living creatures both alive now and in the future. Just as all of humanity is connected ‘horizontally’ across the globe, so too are all past and future life forms bound ‘vertically’ in a continual unfolding of the story of life.

Yet the political and economic institutions of our civilisation are fixated on enjoying the present and unable to account for the consequences of our actions on tomorrow. This may be all too easily observed in our financial behaviour, where individuals, corporations and governments are forever borrowing from the future in order to improve the present.

In the same way, the fossil fuelled party of our capitalist global civilisation is in the midst of a financial and ecological borrowing frenzy from the future. And not only are the spoils of our mastery over nature enjoyed by only a minority of the planet, but in geological terms, they are being consumed within an extremely short time-span.

In a crisis of modernity that could also be re-interpreted as one of ethics and values, how should we reframe our choices and actions in the present, in light of tomorrow?

Surely it is just a matter of standing in the shoes of all future citizens and asking ourselves what sort of planet they would like to live on. Surely our descendants, hundreds and thousands of years into the future, would wish for, and have a right to, the same stable climate and ocean levels that have allowed the attainment of such an advanced and flourishing civilisation today.

It is none other than this consideration for future human beings and other life forms that should form the yardstick by which we set our mitigation targets — not merely what is politically and economically feasible for the industrialised world today.

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Climate Change: What Happens after 2100? by Gregory Trencher is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.


Gregory Trencher

University of Tokyo

Gregory Trencher was previously an intern for the Education for Sustainable Development Programme at UNU Institute of Advanced Studies in Yokohama, Japan. He is currently researching the potential of research universities to address the climate and sustainability crisis as part of a Ph.D. at the Graduate Programme in Sustainability Science at the University of Tokyo. He is also director of the Environmental Learning Institute, a climate change educational initiative for Japanese businesses and corporations.