Panic Part 6 - The IPCC Summary for Policymakers

Love it or hate it, the discussion revolves around this report

Bottom line: I accept the IPCC report as a kind of "hub" around which my view of climate issues must turn. It is important to understand what it is saying, along with its limitations.

Legions of cherry pickers have descended on this report - many to raise alarm, many to rebut, many to blow smoke over it. It is not difficult for a reasonably intelligent person to read the report itself, especially to examine the baskets of cherries emerging from the forest.

Generally speaking, I have found critics of the report to be highly misleading. To call the report "alarmist" is perhaps simply to admit that there is no shortage of worrying facts in the report. For example, the frequently cited concern of the "alarmists" - namely sea-level rise - is completely well documented. To me, the "let them drown" response at COP26 forms the basis of my assumption that the politicians of the world will not do anything meaningful to avoid serious impacts in my lifetime.

The IPCC even hands you an interactive model - your own personal basket - to selectively investigate the conclusions that interest you.

Here are a few things I assume to make my own cherry-picking simpler:

• The IPCC presents 5 scenarios depicting the effect of future changes to C02 emissions. I assume the worst: "SSP5-8.5" as even more optimistic than the best realistic result of international agreements and policy changes. That's 4 degrees by end of the century. It turns out that this doesn't make a lot of difference, either in short term projections (changes locked in) and long term projections (far enough away to be Science Fiction in any case)
• I imagine near-term climate change effects to be like stacking the deck, like say aces representing nasty surprises. The dealer seems to be getting a lot more aces than you might expect but you can't prove anything about any one hand. In the climate case, it is maddeningly difficult to attribute a single catastrophe (say the BC floods) to a "stacked deck". 

So you need to read the entire report with the "stacked deck" analogy in mind. What does the deck look like? What will it look like in the future?

To make things even more interesting, people differ as to their projections of future decks. It is helpful to look out for the degree of certainty but not to entirely ignore nasty but unlikely possibilities.

It is also very important to consult other sources, especially on the question of economic vulnerability. The IPCC has nothing much to say about exponential growth in prosperity, often cited as the means by which the most serious impacts will be avoided, or the reason not to worry about the climate - "we will cope". That's a different issue. It's worth drilling down to those assumptions.

A careful reader will observe the relative absence of "marching bars" graphs so popular with detractors. Marching bars are just barely within the ability of the general public to understand. They will find the graph impressive and take the author's word for what it means. IPCC graphs are sophisticated, with even more subtle interpretations. When they say a picture is worth 1,000 words, sometimes you should assume each picture is worth 1,000 words of explanation. In any case, pause to understand the pictures as well as you can.

The "graph war" is chiefly about claiming that wide variations in climate changes are not unprecedented - business as usual. What is often missed is the alarming rate of change.

--- more later ---