Comprehending the Incomprehensible

The most difficult part of being at COP21 is trying to wade through all of the numbers and acronyms that people are using. How to keep them straight, what they mean, or how did we even reach these numbers in the first place.

image1First let’s start with the numbers around the COPs (or Conference of the Parties), meaning the countries that have signed on to the United Nations Framework Convention on Climate Change (UNFCCC). COP21- this is the 21st meeting of member countries aimed at addressing climate change. None of the previous 20 COPs have ever resulted in a universal, legally binding agreement to cut carbon emissions. This will likely be the first.

Next let’s talk about temperature. The United Nations frames the negotiations at the COPs around temperature, specifically, the amount of global temperature rise that will occur with or without action to reduce greenhouse gas emissions. Here are the temperature increases projected for 2050, dependent on various courses of climate action:

  • +4°C – Expected rise in global temperature if nothing to combat climate change. At this level, sea levels rise, species die, cities flood, and life is very different.
  • 2.7°C – Where we would be with implementation of the current INDCs—(Intended Nationally Determined Contributions), or countries’ emissions reduction pledges, submitted in the lead-up to COP21. Countries made these pledges on their own, without input from the international community.
  • 2°C – This is the number that countries agreed upon before COP21 as the goal for international climate policy (namely, limiting climate change to 2°C of warming, which is thought to avoid the most severe impacts). How to stay under this limit is what’s being debated now at the negotiations.
  • 1.5°C – Low-lying island countries are passionately begging for this to be adopted as the new global target. They believe that if temperatures exceed this threshold, they will lose their homes to flooding and sea level rise.
  • 1° – The amount that the global average temperature has risen already, according to NOAA.  

imageLet’s put these increases in degrees Celsius into perspective. We had an ice age 12,000 years ago that lasted for 100,000 years. We can compare the rate of warmth between the ice age and now vs. our current global warming trends. Coming out of the ice age, we saw a rate of warming of 1 degree for every 2,200 years; in total, the planet has warmed 5 degrees since the ice age of 12,000 years ago. Since the 1990s, however, we’re on a rate of warming of 1 degree every 30 years. This is by far the fastest the earth has ever warmed up – in our lifetimes, we’ve already warmed 1 degree, something which in the past has taken 2,200 years.

How can you translate carbon dioxide emissions into degrees? It is not a perfect science, but it is a science. Earth maintained a balanced level of CO2 particles in the atmosphere until around the 1850s; then, the Industrial Revolution kicked in. From 1850-2000 we have thrown 1035 gigatons into the atmosphere, an average of just under 7 gigatons a year. Since 2000, we have put 440 gigatons into the atmosphere, or 22 gigatons a year. Last year we added 39 gigatons more. As a result, we’ve gone from 280 parts per million of CO2 in our atmosphere in the pre-1850 period to over 400 parts per million today. To hit the magic 2° number, climatologists believe we can’t add more than 880 more gigatons, which we’ll reach in 25 years at our current rate.

A few final numbers to consider:


By 2030 the US has pledged to cut carbon emissions by 26%; the EU has pledged an emissions cut of 40%. Good news, but will need to do more to reach the level of emissions reduction needed to avoid the worst consequences of climate change.

There are 196 countries represented here at COP21, 185 of which have submitted emissions pledges ahead of the talks.

97% or so – This is the number of climate scientist who agree that global warming, or climate change, is human caused.

2 – The number of kids that I would be willing to make significant sacrifices for (my boys Will and Henry).

1 – Number of earths I can leave protected for them.


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