If we do act now

Currently, in 2014, CO2 levels in our atmosphere are just over 400 ppm. Now, this probably won’t mean a lot to you. Not even when you are told that the safe level of carbon dioxide in the atmosphere is 350 parts per million. This post attempts to give ‘ppm’ some context.

All this excess greenhouse gas will lead to actual warming. Not many people know that the warming effects are delayed. They think climate change is not true, because “It’s not really getting any warmer”.

This data visualization below takes you on the path of global implementation of the most optimistic ‘Act Now’ scenario: 

  • The ending of deforestation
  • A halving of emissions associated with food production
  • Global emissions peaking in 2020 and then falling by 3 per cent a year for a few decades.

If that path is taken we will pump out an extra 3000 Gt of greenhouse gas, making atmospheric concentrations of greenhouse gases rise to 650 ppm, associated with a global temperature rise of 4 to 6°C.

CO2 level in our atmosphere and global temperature rise due to climate change
CO2 level in our atmosphere and global temperature rise due to climate change

The delusional thing about global warming is that actual warming effects are delayed. What does that mean? Think about what happens when you put the heating on in your home. It takes a while for the temperature to rise. The same is happening right now in the atmosphere. Once the oceans and the atmosphere are fully heated up – like the radiators in your home – the temperature will go up. However, once it’s nice and warm, we can’t switch off the sun. Or get rid of the greenhouse gas that traps the heat from the sun. In fact, it will stay there for at least one millennium.

Words of support from Professor of Public Ethics Clive Hamilton:

‘If we do act now’ is a powerful visual representation of the threat posed by global warming and I fervently hope it will catalyse many people to accept that the Earth and its human population faces a very nasty future. That may be a despairing conclusion, but it is based on the best science available. We will not know how to respond properly until we have felt the despair a person experiences when they find the courage to face the truth of what the scientists have been trying to tell us.

Notes:

1. The world’s most current data for atmospheric CO2 is measured at the Mauna Loa Observatoy in Hawaii.

2. Why 450ppm is dangerous and why 350ppm is safe

3. Kevin Anderson and Alice Bows, ‘Reframing the climate change challenge in light of post-2000 emission trends’, Philosophical Transactions of the Royal Society, Royal Society, 2008. Referred to in ‘Requiem For A Species’ by Clive Hamilton.

Carbon budget over expenditure

The world is on a so-called all-time carbon budget, set at 2900 Gt of CO2. The definition [1] is as follows:

“A carbon budget can be defined as a tolerable quantity of greenhouse gas emissions that can be emitted in total over a specified time. The budget needs to be in line with what is scientifically required to keep global warming and thus climate change tolerable.”

Carbon budget over expenditure
Carbon budget over expenditure

‘Tolerable’ is widely regarded synonymous with a global temperature rise of 2°C and a target of 450 ppm CO2 in the atmosphere. If we stick to this carbon budget, we have a two-thirds chance of staying below 2°C [2].

I was wondering how much is left. How many years till we blow the 2°C Carbon Budget? And then what?

From 2011 onwards, the remaining CO2 to release was set at 565 Gt of CO2 [3]. On current trends [4], we will blow the global carbon budget and lock in more than 2°C of global warming by 2025.

Everyone agrees, the world will have to start following an emission reduction path soon. Question is, what is the most hopeful judgment about this path? Kevin Anderson and Alice Bows from the United Kingdom’s Tyndall Centre for Climate Change Research have set out the task we face [5]:

  1. Deforestation rates peak in 2015 and fall rapidly thereafter to half in 2040 and 0 by 2060.
  2. Emissions intensity of food production is halved with an extra 2 billion people to feed by 2050.
  3. Global emissions peak in 2020 and then decline by 3% each year, with energy emissions in rich countries falling by 6-7%.

If that path is taken by the world we will pump out an extra 3000 Gt of greenhouse gas. And there’s only about 400 Gt left in our carbon budget. Politicians might have thought, carbon budget? Budgets are there to overspend!

Carbon budget: even with the most optimistic assumptions about a global emission reduction path, we will end up overspending it by a whopping 90%.

Notes

  1. WWF publication ‘Understanding Carbon Budget’
  2. IPCC AR5 Synthesis Report SPM
  3. Source: Carbon tracker initiative 
  4. Source: Interactive by Duncan Clark for The Guardian (with current human emissions of 37 Gt per year, adjusted by 2% per year since the start of 2014 to account for estimated subsequent increases, based on PBL NEAA 2014)
  5. Kevin Anderson and Alice Bows, ‘Reframing the climate change challenge in light of post-2000 emission trends’, Philosophical Transactions of the Royal Society, Royal Society, 2008. Referred to in ‘Requiem For A Species’ by Clive Hamilton.

More reading about the carbon budget

Confused about the new IPCC’s carbon budget? So am I.

9 Simple Charts That Explain The Global Carbon Budget

Two degrees of warming closer than you may think