Impacts of climate change: Our changed world
Climate change is sometimes thought of as something in the future. But 2016 may be looked back at as the year when we truly started living the reality.
This is not just reflected in the maths of record-breaking temperatures but in the impacts on the world around us. Described below are the physical symptoms of the planet's fever which are already apparent: heatwaves, melting ice, bleached coral reefs, rising sea levels, extreme weather.Some of these impacts are already taking a significant toll in human suffering: read for example about the food crisis in southern and eastern Africa. There are links to further reading throughout the text and at the bottom of this page, which will be updated with new information and resources.
The picture above shows a dried up lake during California's prolonged drought (credit Flickr @davidseibold)
2014, 2015, and now 2016 have all broken temperature records - in 2016 the hottest January ever was followed by the hottest February ever, etc... According to the US National Oceanic and Atmospheric Administration, August was the 15th record-setting month in a row. (NASA says the 11th, since it handles the global temperature data slightly differently and uses a different period of comparison). Global temperatures would usually drop off in August compared to July, but unusually, this has not happened this year - even with El Nino withdrawing.
The graph below shows every year from 1880 (click here for animated version). Global average temperatures are higher during summer in the northern hemisphere because the southern hemisphere's temperature, with less land mass, is more stable.
Even more dramatic is this climate spiral which shows deviation from normal for every month since 1850... original website for the spiral here
And if you want another way of looking at it, check out climate change in 167 tiny maps
Why does an increase in global average temperature by, say, 1C or even 2C actually matter? It may seem a small difference, but raising the surface temperature of the whole planet: air, land and oceans, by this amount means a vast amount of additional energy in the system. It is hugely destabilising. It is also unevenly distributed, with land mass areas heating up more. Extraordinary warming has been seen in the Arctic - in February 2016, temperatures across large areas of the Arctic averaged more than 10C above normal.
Click here to see the NOAA map of significant climate change events in 2015, from the State of the Climate report, showing records in heat, drought, melting ice and hurricanes. As monthly temperatures have been higher in 2016, so have the impacts of climate change even been more visible and alarming.
There are fears among scientists that we will now be facing the reality of temperatures rising up to 7 degree Celsius, significantly greater than the upper limit set by the IPCC (4.8 degrees Celsius).
The world has seen an increase in both the frequency and the severity of heat-waves - even close to home: the 2003 heat-wave caused 55,000 to 70,000 deaths across Europe (ref).
India was hit with deadly heat waves in both 2015 and 2016. Temperatures in Phalodi, a city in the desert state of Rajasthan were recorded as a record-breaking 51C on 22 May. The combination of heat and drought killed over 2,500 people in the 2015 heat wave and over 1000 in 2016.
While relief came to India eventually in the form of the monsoon rains, later in summer 2016 countries such as Iraq, Iran and Kuwait still suffered in a Middle East heatwave. For two months Baghdad endured temperatures of 43C and higher nearly every day. Read more
These are a natural part of the ecology in many regions. But rising temperatures and low rainfall increase their frequency and the risk of exceptionally large fires. The number of large wildfires (covering at least 1,000 acres) has almost doubled in the US since 1970.
In Canada, an unprecedented wildfire hit an area which had been previously known mainly as a centre of climate-devastating tar sands extraction., The fire began southwest of Fort McMurray, Alberta. On May 3 2016, it swept through the community, destroying approximately 2,400 homes and buildings and forcing evacuation in Albertan history. It continued to spread across approximately 590,000 hectares in northern Alberta and Saskatchewan, finally being declared under control on July 5, 2016. It is said to be the costliest disaster in Canadian history. Read more.
Much less reported were the multiple smaller wildfires in Siberia, whose smoke was visible from space. Greenpeace Russia claimed that the authorities were underestimating the scale of destruction, and that there was a lack of resources to fight the fires.
Since the 1970s, droughts have become longer and more extreme worldwide, particularly in the tropics and subtropics. Almost a third (30%) of the global land surface was in drought conditions at the end of 2015. Half of this was in severe drought (14%). (Map above from NOAA State of the Climate)
A particularly severe El Nino contributed to the drought in many regions, but drought risk is also increasing because of climate change. The United Nations estimated in May that drought across 13 African countries had put 31 million in need of food aid, with 1.2 million children under the age of 5 suffering from acute malnutrition - and that this would rise to almost 50 million people by the end of the year. Read about the impacts of drought in Eastern and Southern Africa here.
The sea ice extent and volume in the Arctic has been steadily decreasing. The graph on the right shows ice volume each month: what has been called the 'Arctic death spiral'. A closer look at the global maps above shows that northern latitudes are experiencing more extreme warmth than the rest of the planet. This exacerbates the melting. There are also feedback effects: for example darker water not reflecting heat as ice does, and younger ice being less stable. The impacts of the Arctic melting are global because of the contribution to sea level rise. There is also ongoing research into how the higher polar temperatures may affect weather systems in the northern hemisphere.
Most alarming is the potential for the thawing of carbon rich permafrost and the release of trapped methane from the Arctic to add to current levels of atmospheric greenhouse gas emissions in a positive feedback loop. While scientists may disagree how soon this is likely to happen on a significant scale, it is clearly a tipping point that we do not want to cross.
As well as the sea ice of the Arctic, ice sheets on land will have a major impact on the way our climate-changed planet looks. Glacial land ice, covering more than 50,000 square kilometers (20,000 square miles). On the Earth, there exists two ice sheets which cover most of Greenland and Antarctica.
Ice sheets contain substantial quantities of frozen water. Scientists estimate that, if the Greenland Ice Sheet were to completely melt, sea levels would rise about 6 metres. Currently, Greenland has experienced higher than normal temperatures, leading to more than 12% of the ice sheet melting.
Instead of having glaciers above the surface, Antarctica's glaciers lie below the water surface, making them more unstable. With rising sea temperatures, it increases the rate of melting of these glaciers significantly. If all of Antarctica melts, it can contribute to a global sea level rise of approximately 15 metres by 2500.
Sea level rise: the story so far
Sea levels have risen about 20cm since 1870, and the rate of increase is accelerating, with around 8cm of this rise occurring since 1995. The main cause of this rise is shifting from thermal expansion (warmer water expanding) to ice melt.
These rising sea levels are already having an impact on flood risk. The graph on the right shows analysis of the contribution of climate change to coastal floods in the US.
Bangladesh is one of countries most at risk from sea level rise. As well as floods and storms, salinisation of farmland is having a major impact as salt water encroaches, and is a major cause of migration from the coast to the capital, Dhaka, as people are forced to abandon their farms.
And of course, there are countries which are expected to disappear completely if climate change is unchecked. This process is already underway, for example, five small reef islands, part of the Solomon Islands, have recently been lost completely to sea level rise and coastal erosion.
Storms and floods
As well as rising sea levels increasing coastal flood risk, climate change also increases the risk of floods caused by heavy rainfall, and the probability of heavy storms.
The warming of the oceans means for every 1 degree of warming (we were set to pass 1 degrees by the end of 2015) the moisture in the atmosphere increases by around 6%. This extra moisture provides additional energy to the developing weather system, enabling even more moisture to be drawn in to the system.
December 2015 broke records for rainfall and temperature, with flooding across large areas of England, Wales, Scotland and Ireland. Storm Desmond brought heavily moisture-laden air currents (atmospheric rivers): Honister in Cumbria experienced 34cm of rain in 24 hours. On Boxing Day in Yorkshire there was flooding of over 600 homes along the banks of the Ouse and the Foss, and the city of York was flooded. More than 5,200 properties were flooded in Cumbria and Lancashire and 20,000 homes were left without power across the UK. As a result of storms ‘Desmond’ and ‘Eva’, over 16,000 homes in England were estimated to have been flooded.
In August Louisiana was hit with extremely heavy rainfall, with Baton Rouge receiving just under a foot of rain in one day, the total rainfall for August 12-13th being classified as a once in 500 year event. At least 13 people were killed, 150,000 homes damaged and the total cost was estimated at least $8.7 billion. Scientists found that global warming had increased the chances of this event by at least 40% and had probably doubled it.
Although there has been little change in the frequency of hurricanes globally, the strength of hurricanes in the North Atlantic has intensified over the past 40 years. Since the mid-1970s, the number of hurricanes that reach Categories 4 and 5 in strength has roughly doubled. Hurricanes require high humidity, relatively constant winds at different altitudes, and can occur when surface ocean temperatures exceed about 26°C. The rising of warm, moist air from the ocean helps to power the storm. Read more.
Mountain glaciers have also been shrinking. While a much smaller volume of ice than the vast areas at the poles, regular glacial melt is vital as a source of drinking water and crop irrigation, helping to ensure streams continue to run during hot, dry seasons. One of the most significant areas is the Tibetan plateau, the 'Third Pole', which feeds the largest rivers across Asia, including the Yangtze, Yellow, Mekong, Ganges and Indus rivers on which more than a billion people depend.
In the US, Montana's Glacier National Park had 150 glaciers in the late 1800s, and just 25 today (read more).
Boulder Glacier, Montana, in 1932 and 1988:
Coral reef bleaching
[picture shows affected reef in American Samoa, credit: XL Catlin Seaview Survey]
Coral reefs represent less than 0.1 percent of the world’s ocean floor, but help support around a quarter of all marine species. However, they are extremely vulnerable to rising temperatures. Warmer waters cause the algae within corals (which they depend on for survival) to produce toxins. The corals expell the algae. appearing bleached, as their white skeletons are visible. With cooler temperatures, the corals may regain their algae and recover, but if the stress continues for too long they will die.
In 1998, a huge underwater heatwave killed 16% of the corals on reefs around the world. Triggered by the El Niño of that year, it was declared the first major global coral bleaching event. The second global bleaching event that struck was triggered by the El Niño of 2010. The US National Oceanic & Atmospheric Administration (NOAA) announced the third global bleaching event in October 2015 and it has already become the longest event recorded, impacting some reefs in consecutive years, and was expected to contine until the end of 2016.
2016 has been a very damaging year for the reef, with it having to endure El Niño and further global warming, leading to a significant increase in the water's temperature. The temperature of the water did not drop enough for the reef to recover, and has lead to the death of about one quarter of the reef, including two-thirds of coral in the northern section of the reef (which covers 700km). Earlier this year, an aerial survey found that the northern section was the most severely affected, with approximately 95% of the reef was severely bleached.
Japan's Sekisei lagoon's coral reef has suffered substantially due to warmer sea temperatures, where almost 75% of the reef has died because of bleaching. Approximately 90% of the reef has been bleached. The reef covers 400sq km.
Although reefs can recover, this requires the temperature of the water to cool down and can take about 15 years for a full recovery.
As well as rising temperatures, ocean acidification is also a serious issue for coral reefs and other sea creatures. As oceans absorb excess carbon dioxide, the waters become more acidic. This is likely to cause hundreds of marine species to either die out or migrate elsewhere. Another issue is, for those creatures that do survive in more acid waters, especially those with shells (clams, oysters and snails for example), their shells would be left puny and shrunken.
Other ecosystem impacts
Ecosystems on both land and sea are starting to be affected by climate change.
Mangroves are trees or shrubs that grow in tidal, mainly tropical, coastal swamps. They play an important role in ecosystems; many species of fish use them as nurseries, they filter sediment, protect coral reefs and seagrass meadows and also providing protection to coastal ecosystems and shorelines from storms and tsunamis. One of the main areas of concern for mangroves was off Australia's Gulf of Carpentaria earlier this year (2016). It is thought that a combination of dry conditions (lack of rain), warm air and sea surface temperatures led to the devastation of approximately 7,000 hectares of mangroves.
One impact that is easily observed is that due to rising temperatures, plant/vegetation cycles have been affected which has resulted in them either blooming later or earlier than usual, which affects species that rely on them directly. With rising temperatures, there have been a migration of species to cooler areas in order to survive. If temperatures continue to rise at the same rate, experts have predicted that by 2050, a significant amount of species face extinction.
With rising sea levels, this means that saltwater can intrude into freshwater systems, resulting in the relocation, or deaths, of even more species. This damage would be critical to any food chain or ecosystem affected.
Because humans have already had a devastating impact on the earth's biodiversity, through habitat loss, pollution and over-fishing for example, the impact of climate change may be hard to isolate. But in 2016 it was announced that the Bramble Cay melomys was the first mammal species to have become extinct specifically because of climate change.
Some further reading about the impacts of climate change...
As well as the links in the text, here are some more links to information that may be of interest.