Breaking down the IPCC special report on climate change and our oceans

This week the IPCC released a special report focusing on how climate change is impacting our oceans and predicting the scale of future problems. Here I provide a summary of the key findings and clearly explain some of the bigger issues.

penguin
The antarctic ice sheet and other parts of the cryosphere are disappearing at an alarming rate according to the IPCC special report

On 25th September at the International Panel on Climate Change (IPCC) meeting in Monaco researchers unveiled the most in depth analysis of climate change and its effects on our oceans to date. Titled ‘Special Report on the Ocean and Cryosphere in a Changing Climate’ it is the third special IPCC report of 2019, but the first to focus exclusively on effects in the oceans and areas of frozen water known as the cryosphere. The report was written by 104 leading scientists from 36 countries and references 6,981 different pieces of research. Safe to say it is a highly reliable and accurate look at the state of our oceans. After its release major news outlets across the world shared the key findings in a barrage of facts, stats and opinions. But it left a lot of people feeling confused and overwhelmed. So in this article I have attempted to break down the 1,170 page report and summarize the key findings as well as clearly explain some of the big problems we are facing. After all this is important stuff and we all deserve to understand what’s happening to our oceans.

Key findings

The report covered every single possible way climate change has affected our oceans and will continue to do so in the future. Needless to say that this means there is a lot of findings to trawl through. But certain facts and figures cut through the rest and have been widely reported across major media channels. Here is a list of the key ones…

  • It is now ‘virtually certain’ that ocean temperatures have been rising continually since 1970.
  • The oceans have absorbed over 90% of the excess heat created by global warming, without which we would already be dead.
  • The rate at which mass was lost from the Antarctic ice sheet tripled between 2007 and 2016 and doubled in Greenland over the same time.
  • Glaciers across the world are expected to lose 80% of their ice by the end of the century under current carbon emission levels.
  • Under high carbon emission levels the mean global sea surface will rise by 1.1m by 2100 effecting around 700 million people worldwide.
  • Surface ocean waters are becoming increasingly acidic and dissolved oxygen levels are reducing down to 1000m depth.
  • Since 1950 marine species from all main groups have undergone a shift in geographical ranges caused by a changing ocean. This will occur much more frequently and to more species in the future.
  • There is now a high risk of losing biodiversity, biomass, structure and function of key marine ecosystems with severe knock-on effects to coastal communities, tourism, food security and the global economy.

Sea levels rising

One of the main take-away messages of the report is that climate change will result in serious sea level rises over the next century and beyond as the cryosphere continues to melt. It is believed that sea level increases up to 2050 are already locked in under our current carbon emissions and potentially unavoidable. If necessary action is not taken then the report predicts sea levels could rise by a global average of 1.1 metres by 2100. This will affect up to 700 million people who live on islands or in coastal cities and communities. But one of the most frightening consequences will be that extreme sea level events that previously happened once a century could become annual events by 2050. This will mean extreme flooding of these areas will become much more common. Low lying areas will also be much more prone to tropical storms which will become more common and damaging in the future. Check out a map of at risk locations for yourself below.

map
A global map of cities at risk from rising sea levels by 2050 (produced by the BBC)

Permafrost melting

The report focuses heavily on how melting glaciers and ice sheets in polar regions will contribute to rising sea levels. But one part overlooked by the media is the melting of permafrost regions. These include large parts of Canada, Siberia, Greenland and high altitude regions where the ground remains frozen year-round, but not necessarily covered in snow or ice. The melting, or more accurately thawing, of these areas will have serious repercussions for climate change acceleration. That is because large amounts of carbon are currently trapped in the ground by freezing temperatures. But when they are warmed above zero degrees all that carbon will be freed up and released into the atmosphere. The report highlights the melting of permafrost as a potential tipping point past which climate change will become uncontrollable.

permafrost
The permafrost in this arctic tundra contains millions of frozen tonnes of stored carbon

Species shifting

As well as human populations being affected by a changing ocean many marine species are also being forced to relocate because of oceanographic shifts. Since 1950 it is believed that species from every major marine group have been forced to shift their geographical ranges. As the oceans continue to transform from the effects of climate change this will only get worse. A big factor is melting ice sheets that are important to lots of arctic species such as walruses, penguins and polar bears that call them home. Oxygen depletion in the upper layers of the ocean, caused by rising temperatures and agricultural run-off, are also causing species shifts up and down the water column. There are also knock on shifts caused by species movements. For example range shifts in small pelagic fish further away from coastlines means seabirds have to fly a significantly greater distance to find food which is energetically very costly. As changing conditions force greater range shifts in the future it is likely that many marine species just won’t be able to adapt to their new homes quick enough to survive.

Ocean acidifying

Another big focus of the report is the rate at which the upper layers of the ocean are becoming acidic. This is a result from increased levels of CO2 that not only trap heat in the atmosphere but also dissolve in the oceans forming carbonic acid. The experts believe there has already been a substantial shift in the acidity of the oceans but that it will become much more noticeable and destructive in the future. The species under threat from ocean acidification include crustaceans and molluscs but most importantly corals. Coral reefs are already suffering greatly from bleaching caused by warming oceans leading to a breakdown of their symbiotic relationship with photosynthetic algae. Ocean acidification will make it easier for corals to bleach and harder to recover from heat waves that will become more common as global temperatures increase. The report warns that even at reduced levels of warming 90% of global corals could disappear completely by 2050. There is also a risk that coral reefs will be lost completely by the end of the century.

Coral Garden Reflections. Indonesia
Coral reefs are already under threat from climate change and could be the first marine ecosystem to completely disappear

Ecosystems disappearing

Coral reefs are not the only marine ecosystem under threat from climate change. Almost every single habitat from the surface to the seafloor are being impacted in some way. As more species become effected by shifting ranges caused by warming waters, ocean acidification and decreasing oxygen then marine food webs are likely to break down. But not only will marine ecosystem breakdowns negatively impact the marine species that live in them. They will also lead to serious consequences for human populations. The report warns that ecosystem collapses will lead to fisheries following suit which not only affects food security for a growing population but also people’s livelihoods, coastal communities, indigenous groups and economic stability. There will also be financial costs to losing natural coastal protection, potential medicines, tourism and recreational activities. The report also warns that the loss of ecosystems will result in damage to the cultural identity of our planet.

Is it too late?

The IPCC report does not make for enjoyable reading for marine conservationists, climate activists or anyone else who plans on living on Earth in the future. It shows us unequivocally that we are approaching a tipping point past which sea level rise and ecosystem breakdowns will become unavoidable. However it is not too late just yet. The report is a glimpse into the future of current carbon emissions and plans to cut them. However the authors believe that increased efforts to reduce fossil fuel consumption and drastically reduce carbon emissions in the next decade will reduce some of these issues in the long run. They are recommending at least a 45% global cut by 2030, which we are not currently on track to do, but is possible with large scale system changes. Speaking to the BBC Dr Jean-Pierre Gattuso, a lead author on the report, said “after the demonstrations of young people last week, I think they are the best chance for us” referring to the youth climate strikes. He went on to say “they are dynamic, they are active I am hopeful they will continue their actions and they will make society change”.

school strike
Over 4 million people took part in the global climate strike on 20th Spetember

If you are feeling brave you can read the entire report for yourself at the IPCC website here.


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