Economist: THE Intergovernmental Panel on Climate Change (IPCC), a gathering of scientists who advise governments, describes itself as policy-relevant and yet policy-neutral. Its latest report, the third in six months, ignores that fine distinction. Pressure from governments forced it to strip out of its deliberations a table showing the link between greenhouse gases and national income, presumably because this made clear that middle-income countries such as China are the biggest contributors to new emissions....