Limit to 1.5℃

Panels with solar cells and wind generators on a green field with blue sky

The Intergovernmental Panel on Climate Change (IPCC) released its latest report describing how we can, as a planet, reach the goal of no more than 1.5℃ increase in global temperature. This is not going to be a simple goal to reach, and it is going to require some significant changes.

Human activities are almost certainly the cause of around 1℃ of global warming since pre-industrial times, and are on track to hit 1.5℃ between 2030 and 2052, according to the report.

The World Resources Institute has a good article detailing eight things that you need to know about this report and making it much more digestible.


Source: IPCC (2014); based on global emissions from 2010. Details about the sources included in these estimates can be found in the Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change

An obvious target for carbon reduction is to switch more of the planet’s energy to renewable sources. Energy (electricity, heat and other) contributed 35% of the greenhouse gas emissions globally. That is over double the contribution of transportation. Reducing this sector will be essential to meeting the 1.5℃ target.

That means dramatically reducing dependency on coal and natural gas for electricity generation, and increasing renewable sources like wind and solar. 

Other static uses of carbon based fuels, such as heating water and homes, will also need to be reduced. Electrification may hold some of the answers to that as well, switching from gas and oil fired water heaters and home furnaces to electric water heaters and heat pumps.

While we have good techniques for achieving this, actually implementing them, especially those that require individual households and businesses to replace their existing equipment, are not going to be simple.


Transportation is another case where the solutions are well understood, and the technology is becoming more available every year, but switching even all new vehicles sold to using clean energy, whether that is battery or hydrogen fuel cells, is not something that is going to happen quickly. Various countries have tried to commit to that goal by dates in the 2030 to 2040 range, but that does nothing for the over 1 billion cars already on the roads that continue to burn fossil fuels and contribute to the warming.

Estimates suggest there were 70 million new cars sold in 2016. At that pace, assuming you could get all new cars sold to be fossil fuel free, it would still take 15-20 years to replace all the cars currently on the road. That suggests that transportation will continue to contribute to the problem well into the second half of the century, and well past the 2030 goal for the 1.5℃ target.

It is going to take some far more aggressive schedules than any currently proposed to be able to significantly reduce the carbon footprint from transportation by 2030.


If switching people to cleaner energy sources and cleaner transportation were hard, switching people from a heavily meat based diet to a mainly plant based one is going to be even harder.

Switching to a more plant based diet would be a win on multiple fronts:

  • Less methane from livestock (methane is a more potent greenhouse gas than carbon dioxide) would result in a direct reduction in greenhouse gas emissions;
  • Feeding plants to livestock to feed humans is a lot less efficient than having the humans consume the plants directly. That means more food from a smaller area, potentially reducing the need for some or all of the deforestation that is removing the trees which help clean the carbon dioxide from the atmosphere.


There are other areas that are often cited, such as cement production, which have a negative impact on greenhouse gas levels too. Hitting the 1.5℃ target is going to require innovation across the board. The energy, transportation and agriculture sectors already have good technical solutions today. All that is needed is the motivation to fix the problem and a willingness to change.

Whether or not you believe human activity is the cause of the problem (and, to be clear, the evidence is overwhelmingly in favour of human activity being a major contributor to global warming over the last century, and the continuing acceleration in that warming), it seems very clear to me that we should be doing everything in our power to manage it.

The argument that “we did not cause it, so we cannot fix it” does not hold water at all. There have been many things that were not caused by humans that we have worked to find ways to mitigate the effects of. Living in an earthquake region, it is very clear that there are some things we cannot stop, but we have developed technologies and regulations that have reduced the impact of earthquakes. We can, and should, do the same for global climate change.

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