The IPCC's Special Report on Oceans and Cryosphere in a Changing Climate has revealed how Earth's oceans and frozen and ice-covered lands have been 'taking the heat' of human-induced global warming, reports CDKN's Mairi Dupar.

The IPCC’s Special Report on Oceans and Cryosphere in a Changing Climate, launched last week in Monaco, should transform the way people think and talk about our planet.

It assesses the scientific evidence on changes in our atmosphere and its interaction with oceans and Earth’s frozen areas, including: snow-covered land; glaciers; ice sheets; sea, lake and river ice; permafrost; and seasonally frozen ground.

The Special Report brings to light in a clear, newly-framed way, how human-induced climate change is making ice caps and glaciers melt, and is warming and changing the chemistry of the oceans.

These changes are already well underway, even though most people in the world can scarcely perceive them yet. Over the last few decades, global warming has led to mass loss from ice sheets and glaciers, reductions in snow cover and loss of Arctic sea ice.

Since 1970, the global ocean has taken up more than 90% of the excess heat in the climate. Warming of the ocean has made surface ocean waters more acidic, because the ocean has absorbed carbon dioxide.

A wake-up call for massive changes on the horizon

Although still largely invisible, these changes will bring trouble in decades to come for the hundreds of millions of people living on exposed coastlines and dependent on safe, regular flows of water from high mountain ecosystems.

Melting ice from the Greenland and Antarctic ice sheets is speeding up the rate of sea level rise. On average, global sea levels rose at 3.6 mm per year from 2006-2015: two and a half times faster than the rate of sea level rise last century.[1]

680 million people in low-lying coastal zones are now at risk from rising oceans and this will reach a billion people by 2050. Equivalent numbers of people live in the world’s high mountain regions, which are greatly affected by thawing and ice loss.[2]

This rate of sea level rise will continue at least until the middle of the century, even if greenhouse gas emissions from human society were to drop suddenly. That’s because of the increased concentrations of greenhouse gases in the atmosphere already and the lag in the response of Earth’s systems.

“The Special Report illustrates how much change is already occuring in the Earth’s systems – as a result of global greenhouse gas emissions - and the utter urgency of making investments today, to prepare exposed and vulnerable people to deal with the unfolding impacts,” said Dr Shehnaaz Moosa, CDKN Director.

Adaptation investments can limit the damage

Some communities in highly exposed mountain environments and particularly fragile coastal environments such as atoll island nations are already living on the edge.

CDKN and its partners have seen this – for instance – in India’s Himalaya region, where communities have been documenting the risks of climate change in their fragile ecosystems. Communities in Leh, India received CDKN project funding to instal a weather monitoring station and improve the tracking of the climate changes. A radio series by local teenage girls and a communications campaign by Indian NGO SEEDS helped raised awareness of extreme weather events and the hitherto invisible risks to these communities.

A CDKN-supported project in Lima, Peru similarly documented the accumulated and invisible risks of urban erosion and environmental degradation, made worse by climate change, in this coastal mega-city.

Leaders of Pacific Island nations have been calling for stepped up global action to mitigate climate change for years. They face the prospect - openly discussed by President Heine of the Marshall Islands - that their populations have perhaps only a few years before they must abandon their lands to rising seas.

Significantly, the IPCC’s Special Report finds that societies are far better off investing in adaptation solutions now than delaying action and seeking to clean up the damages later. The types of adaptation actions considered by the IPCC include: wetland conservation and restoration, hard coastal protection and managed realignment or ‘coastal advance’ measures where the sea is allowed to flood certain areas in a managed way.

The best adaptation is mitigation

As with previous IPCC reports, though, the biggest takeaway message is that mitigating climate change by cutting global greenhouse gas emissions is by far the best way to limit damage to Earth’s coastal and icy ecosystems and the repercussions over the rest of the planet.

Look beyond 2050, when we may hope for today’s children to mature with dignity and safety, and the IPCC finds with ‘very high confidence’ that “ocean and cryosphere changes and risks by the end-of-century (2081-2100) will be larger under high greenhouse gas emission scenarios, compared with low emission scenarios.”[3]

For example, cutting emissions deeply now (to limit global warming to 2C or less) would see overall sea level rise reach 0.43 metres by 2100. Under a high emissions scenario, sea level rise would be around double this, at 0.84 metres by 2100.[4]

To see just what a difference those figures would make in a densely populated, low lying delta like the Ganges-Brahmaputra-Meghna Delta in Bangladesh, try the Surging Seas tool, developed by Climate Central and tested with CDKN support. It shows just how much land area, and how many more people would be affected by a few centimetres’ rise.

The devastating news is that global greenhouse gases are not only rising, but rising at an accelerating rate: what the New York Times described as a ‘speeding freight train’.

Once more, science has thrown down the gauntlet to governments, business and citizens to work together for a net-zero emissions present, leading to a more resilient, sustainable future.

This week’s IPCC Special Report is a clarion call to take the science seriously, filled with astonishing and alarming evidence.

Read the IPCC’s Special Report on Oceans and Cryosphere in a Changing Climate.

[1]1.4 mm per year from 1901-1990.

[2] 670 million people live in high mountain regions today; 10% of the world’s population.

[3] Chapter 1, Executive Summary.

[4] Summary for Policy Makers, B3.1.

Image: Courtesy Stig Nygaard