For years, scientists and policy experts have focused on a simple target in hopes of avoiding catastrophic climate change – keep average global temperature rise to no more than 2°C above pre-industrial levels.
However, the release of greenhouse gases through human activities has had a stronger negative impact on our climate system than scientists initially predicted. As a result, world leaders have recognized the need to raise the level of ambition of our global greenhouse gas reduction targets and aim to limit global temperature increase to 1.5°C.
It’s important to note that 2°C is an average temperature increase across the globe and that some areas – such as the polar regions – are expected to warm much faster and see a temperature rise much higher than 2°C.
So Where Did 2°C Come From?
The origins of the 2°C limit are not with the scientific community, but rather from a Yale economist, William Nordhaus. In his 1975 paper “Can We Control Carbon Dioxide”, Nordhaus “thinks out loud” about setting a target to keep climatic variations within a normal range. He emphasized that science alone could not set the limit, but that both society’s values and available technologies must be taken into account. His conclusion was that a reasonable upper limit would be a doubling of pre-industrial carbon dioxide (CO2) levels, which he believed equated to a temperature increase of about 2°C.
In 1990, a team of researchers from the Stockholm Environment Institute (SEI) wrote a report that stated, “Temperature increases beyond 1°C may elicit rapid, unpredictable, and non-linear responses that could lead to extensive ecosystem damage.” SEI argued that limiting climate change to 1°C would be the safest option but recognized even then that 1°C was probably unrealistic, so 2°C would be the next best limit. They suggested that there was nothing ‘safe’ about a two degree limit.
In 1992, world leaders signed the United Nations Framework Convention on Climate Change (UNFCCC) at the Earth Summit in Rio de Janeiro. Article 2 of the convention commited countries to stabilising greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system. The UNFCCC stopped short of defining the level at which climate change became “dangerous”.
In 1996, the European Council of environment ministers became the first political body to lend formal support to the 2°C limit.
In 1998, 193 countries signed the world’s first binding agreement to cut emissions: the Kyoto Protocol. Although the Kyoto protocol did not explicitly state the 2°C limit, media reports at the time linked the treaty to achieving this goal.
The first time the 2°C limit was included in an international climate agreement was in 2010 when countries signed the Cancun Agreements. One of the main goals was to “establish clear objectives for reducing human-generated greenhouse gas emissions over time to keep the global average temperature rise below two degrees.”
The impacts of a 2°C world are now widely agreed upon by the scientific community as being extremely dangerous and potentially catastrophic. As an example, coral reefs are already being devastated by the 1.1°C rise in global temperature we’ve seen to date. The Great Barrier Reef in Australia now regularly bleaches, with more and more corals unable to recover. These beautiful ecosystems, full of colour and abundant life are rapidly becoming ghostly and dead. Scientists predict that an increase in global temperature of 2°C would put 98% of reefs at risk of bleaching.
So why have we stuck with the 2°C target? The Intergovernmental Panel on Climate Change’s co-chair, Thomas Stocker has said, “The power of the 2°C target is that it is pragmatic, simple and straightforward to understand and communicate, all important elements when science is brought to policymakers.”
In 2015, world leaders met in Paris and given the most recent scientific evidence, they started the discussion that would lead to a more ambitious target than 2°C.
What is the Paris Agreement?
The Paris Agreement became effective on November 4th, 2016. With 195 signatories, it is the most comprehensive global climate agreement to date. The goal of the agreement is to keep global temperature rise to “well below” 2°C above pre-industrial levels and to pursue efforts to limit the temperature increase even further to 1.5°C, while aiming for net zero emissions in the second half of the century.
Key to its success is the ability for each county to set individual pledges about what they will do to address climate change within their borders. These pledges are called Nationally Determined Contributions (NDCs). The Paris Agreement is designed to get better over time using a “ratchet mechanism” as illustrated below.
Stage one of the Paris Agreement was completed in 2015 when each country set their climate pledges (NDCs). Unfortunately, current NDCs do not put us on an emissions pathway to meet even the 2°C target, let alone 1.5°C.
The next stage in the Paris ratchet mechanism is a Facilitative Dialogue in 2018 (FD2018). FD2018 will be an open discussion to inform the preparation of the second round of climate pledges, which all governments, including our own, need to submit by 2020. The facilitative dialogue is an opportunity to collectively look into options on how current NDCs can be revised and new ambition can be generated to strengthen individual Parties’ contributions by 2020.
What Difference Does a Degree Make?
Here in Canada we can easily see temperature fluctuate up or down by more than 10 degrees in a single day. So what difference does a degree make? Well, when talking on the scale of global averages, one degree makes a world of difference.
Here’s what’s at risk with each degree of global temperature rise above pre-industrial levels:
What does 1°C look like?
- The Amazon Rainforest is impacted by regular drought
- California is subject to mega-droughts, desertification and intense wildfires
- World cyclones use warm ocean waters to become more severe
- Small island states are abandoned and sea level rises
What does 2°C look like?
- The world’s great coral reefs near complete extinction, eliminating an essential habitat
- Summer monsoons in northern China will likely fail, and agricultural production will suffer
- Flooding in Bangladesh will worsen
- In the Andes, loss of glaciers will result in reduced summer run-off and subsequent water shortages will be devastating for nations such as Peru
- Crop failure and hunger are likely to increase across Africa
- Seas will be on their way to rising 5 to 7 metres (Miami and Manhattan are under water at five-metre sea level rise)
- The Greenland ice sheet will begin melting irreversibly
- The polar bear would be all but extinct, with walruses not far behind
- Europe likely will be hit every second year by heat waves like the one in 2003 which killed 35,000 people, caused $12 billion in crop losses, and reduced glacier mass by 10%
What does 3°C look like?
- Northern hemisphere free of glaciers and ice sheets
- Sea levels 25 metres higher, placing coastal cities underwater
- Amazon Rainforest turns to savannah, including drought and mega-fires
- Increasing areas of the planet uninhabitable due to drought and heat
- Hurricanes increase in power by half a category above today’s top-level Category 5
- World food supplies critically endangered, resulting in hundreds of millions of climate refugees
- Arctic warms, melting permafrost in the boreal forests, triggering the release of methane, a greenhouse gas more than 20 times as powerful as carbon dioxide
What does 4°C look like?
- Hundreds of billions of tons of carbon locked up in the Arctic permafrost enter the melt zone, releasing global warming methane and carbon dioxide in immense quantities
- The West Antarctic ice sheet completely collapses, further raising sea level
- New deserts spread across Italy, Spain, Greece, and Turkey
- Summer temperatures may reach 48°C in Switzerland
- The Alps no longer have snow
- Europe’s population may be forced into a “great trek” north in search of a more hospitable climate
Any level of global temperature rise will change the way we live and there is nothing ‘safe’ about a 2°C limit. This is because 2°C represents an average temperature rise across the globe. In Canada, we will see the warming occur much faster. At the current rate, scientists say the global average temperature could rise 4°C by the end of this century! In Canada, this means an average temperature rise of 8°C for the south of Canada and upward of 12°C for Northern communities.
Climate change will wreak havoc on the global food system. For each 1°C of warming, crop yields decline. Corn, wheat, rice, and soy are especially vulnerable. These four food crops make up two thirds of human caloric intake.
Further, rising concentrations of carbon dioxide are threatening global nutrition by reducing levels of nutrients in food crops. Zinc, iron, copper, magnesium, and calcium could decrease by 5 to 10% in staple crops as carbon dioxide levels rise.
What Will it Take to Meet the Paris Agreement Target?
Canada has developed the Pan Canadian Framework on Clean Growth and Climate Change to work towards meeting our obligations under the Paris Agreement. The emissions reduction plan is illustrated in the image below.
A recent report from the United Nations highlighted Canada is highly unlikely to meet our 2030 target unless we significantly ramp up our ambition. Canada’s climate pledges to date are leading us into a world of significant and catastrophic climate change. We must do more.
According to recent research, this is a common theme. Globally, we have a 5% chance of limiting warming to 2°C, and only a 1% chance of keeping man-made global warming to 1.5°C. These stark projections are not from a “business as usual” scenario, but rather are based on data which already show the effect of emission mitigation policies. Recent research also shows that we may have already locked in 1.5°C of warming even if we magically reduced our carbon footprint to zero today.
Further, the IPCC’s calculations suggest hopes of preventing temperatures from ever crossing the 1.5°C threshold are slim to none. But they highlight that options to temporarily exceed the target and return to lower temperatures later in the century could still be on the table.
We must significantly ratchet up Canada’s ambition in 2018 during the Facilitative Dialogue (FD2018). Immediate, bold action is required. If Canada is serious about keeping global temperature increase well below 2°C, we will need to set new plans for climate action that are action oriented and lead us to a rapid decline in national emissions. By raising ambition, we will increase our chances of avoiding catastrophic human-induced climate change. The longer we wait to take action, the more extreme the emissions declines will need to be.
What Could the Canadian Government Do?
- Ahead of FD2018, Canada must seek to provide clarity on the conditional aspect of their international climate commitments and the associated additional ambition that could be unlocked through greater means of implementation and cooperation.
- The government must be honest about the gap between its international climate targets and the required emission pathways consistent with keeping warming well below 2°C and pursuing efforts to limit warming to below 1.5°C.
- Canada must start the discussion with other countries to identify barriers to those countries’ international climate targets, and work to help address issues in order to increase ambition.
- The government must play a constructive role in moving towards outcomes on other aspects of international climate change work, such as loss and damage, adaptation and finance.
- Canada can lead the way by submitting bold international climate commitments well ahead of the 2020 deadline in order to influence strong action from the international community.
- The government must reflect this increased ambition in the Pan-Canadian Framework on Clean Growth and Climate Change by revising actions so that they’re in line with the more ambitious 1.5°C target.
What Can You Do?
Start by contacting your Member of Parliament:
- Tell them we need to listen to our scientists, set our ambitions much higher, and plan actions accordingly.
- Put pressure on them to be honest about the scale of change needed to meet the climate challenge.
- Ask them what their plan is to ensure Canada raises ambition in the FD2018 process.
- Demand that Canada submit strong climate pledges when it has the chance to do so in 2020.
Write a Letter to the Editor:
- Explain that Canada has the opportunity to become a world leader in climate action during FD2018
Get Active on Social Media:
- Let the world know that you’re ready to raise ambition and take bold steps to address climate change.
Warren, F.J. and Lemmen, D.S., editors (2014): Canada in a Changing Climate: Sector Perspectives on Impacts and Adaptation; Government of Canada, Ottawa, ON, p. 27 Figure 3
Chuang Zhao, et al., “Temperature increase reduces global yields of major crops in four independent estimates,” PNAS, August 29, 2017
Chuang Zhao, et al., “Temperature increase reduces global yields of major crops in four independent estimates,” PNAS, August 29, 2017
Bloom, et al., “Increasing CO2 threatens human nutrition,” Nature, April 2014
U.S. Global Change Research Program, 2016