Yet, one could argue the report – in a few places – goes too far in attempting to stay-on message by glossing over some of the thornier issues in climate science and not sufficiently qualifying projections.
For example, the highlights report says: “…data records have grown longer and climate models have become more comprehensive, earlier predictions have largely been confirmed. The only real surprises have been that some changes, such as sea level rise and Arctic sea ice decline, have outpaced earlier projections.”
Legitimate climate scientists, who have published in the peer reviewed literature, could easily nit pick this sweeping statement. Countering the assertion “earlier predictions have largely been confirmed”, an August 2013 paper in Nature Climate Change concluded that computer models simulated over four times as much warming compared to reality since 1998 (note: the report does discuss the reason for this, i.e. a short-term slowdown in surface warming, in its “science supplement.”). And while the decline in Arctic sea ice has occurred faster than model projections, Antarctic sea ice has actually increased (for complicated reasons, which don’t refute global warming) while many models predicted the opposite.
Just as the report’s discussion of the success of past predictions could be better qualified or more complete, so could some of its predictions about the future.
For example, the chapter on the Northeast predicts a 60-day per year increase in the number of 90 degree or warmer days by mid-century in the northern Mid-Atlantic region. In Washington, D.C., for example, that would imply the current average of 36 90+ degree days would increase to 90 – or the equivalent of the entirety of June, July, and August.
[. . .]
While the number of 90+ degree days have trended upward in D.C. over time, a rather remarkable acceleration in the long-term trend would be required for this projection to become reality.
Oversimplified statements and projections that seem over the top can do damage to an otherwise outstanding body of work – which is beautifully and innovatively presented. Over 300 excellent scientists contributed to this report.