Jean Jouzel, the scientific sponsor of in the Air to the Earth, costs, french Glaciologist, climatologist and vice president of the scientific group of the IPCC from 2002 to 2015 we explains comprehensively where we are compared to the climate change then presents the IPCC in a second interview!

Overall presentation of climate change (part 1)

Presentation of the IPCC

Today, he has more doubt on the fact that man is responsible for the climate change that we are currently living. Evidenced by the IPCC which we hear so much about, and on which you will find details below.

We would like to tell you about the IPCC, because this is not only a dozen people who are trying to understand what climate change is in their corner. The IPCC summarizes all of the scientific work, which have been published and verified by the scientific community (i.e. thousands of people).

You will find here the latest report of the IPCC (the 5th) which dates from late 2014 and the french summary report which is available there. If you do not want to read 40 pages look only at the following charts which are sufficient to measure the magnitude of the problem facing our society. On the other hand if you speak English and you like to read then the synthesis report with only 32 pages is very well done to give you an overview.

To learn more about the work of scientists who have revealed that climate change, go see ‘The ice and the sky’ movie on the life of Claude Glorius, who is beautiful.

We will now present you various graphs that show the magnitude of the current problem and which you can find in previous reports.

First we present the four scenarios used for communicating on climate change:

• RCP 2.6
• RCP 4.5
• RCP 6.0
• RCP 8.5

RCP means “Representative Concentration Pathways” and are described in detail here. These are baseline scenarios of changes in radiative forcing over the period 2006-2300. Radiative forcing is the difference between the radiative energy received and the radiative energy emitted by a given climate system (here the Earth). It is expressed in W/m2. When we have a positive radiative forcing for the Earth, it will have the effect of heat and thus increase the global temperature. This is what is happening at the moment where we had in 2011 a radiative forcing of 2.84 W/m2. More radiative forcing is important, more the Earth will warm up. Here is the explanation of the four scenarios drawn from Moss et al. Nature 2010:

GHG means gas greenhouse. We spoke in eq – CO2 that is Equivalent of CO2 because there are also other gases to greenhouse effect than CO2 as Methane (CH4), nitrous oxide (N2_O), ozone (O3) or even the water vapor (H2O). It takes so all of these gases are back to CO2 using global warming potential (GWP). Is thus an aggregate measure of the greenhouse gas to facilitate comparisons between the different scenarios.

The RCP are associated with more or less significant CO2 emissions and therefore to a future global temperature:

If doing a reading of this graph, we see that the scenarios diverge from 2030. The window for action to combat climate change is therefore greatly reduced. If we are not reducing our emissions dramatically in the coming years, we cannot go back. It is therefore a real race against the clock that humanity faces today.

Here are the temperature and precipitation changes our world will be facing two extreme scenarios:

There is also that in the worst case scenario (RCP 8.5) we have an increase in global temperature of + 4 ° C, resulting in local increases up to + 9 ° C approximately. This is totally unsustainable for the societies in which we live and it would also have enormous consequences on populations and ecosystems.

In the best of scenarios (RCP 2.6), the increase in global temperature is limited which also enables to limit the local increase in temperature. This is a much more comfortable scenario for our societies current but not easily achievable without significant efforts of us all.

We can also see the effect of climate change on rainfall. In the RCP 8.5 scenario, there is only very little precipitation and therefore regions, already very dry world will become even more. This will therefore have consequences that populations can no longer inhabit these regions and therefore the number of climate refugees explodes. The wetlands as they receive benefits of precipitation and are thus exposed to benefits of flood risk and everything what one knows. In all cases, significant changes are to be expected, changes which companies will have to adapt quickly.

Climate change is also a significant increase in extreme weather events (article short and interesting here): longer heat waves, extreme rainfall, more large number of cyclones etc. That is why it takes significant adaptation of societies to climate change to reduce their vulnerability.

Overall there are two main pillars of fight against climate change:

• the mitigation of greenhouse gas emissions, to limit the increase in global temperature of the Earth
• adaptation to climate change, to reduce the vulnerability of societies to the temperature rise and its consequences

Finally on the presentation of climate change, he must also be careful to distinguish between climate variability from human-induced climate change. Indeed, it is not because we have a winter cold that climate change is no longer there. Let’s watch the time scale associated with the various phenomena and the trend that can be disconnected. We are not expanding, but we will discuss this point in a future interview!