Branko Milanovic writes:
As income inequality increased in the past quarter century in most parts of the world, it was strangely absent from mainstream economic discussions and publications. One would be hard-pressed, for example, to find many macroeconomic models that incorporated income or wealth inequality. Even in the run-up to and immediate aftermath of the 2007–2008 financial crisis, when income inequality returned to levels not seen since the Great Depression, it did not elicit much attention. Since then, however, the growing disparity in incomes between the rich and poor has taken a place at the top of the public agenda. From Tunisia to Egypt, from the United States to Great Britain, inequality is cited as a chief cause of revolution, economic disintegration, and unrest.
This feeling that the incomes of the rich and the poor have diverged in part reflects reality: between the 1980s and mid-2000s, income inequality rose significantly in countries as diverse as China, India, Russia, Sweden, and the United States. The Gini coefficient, a measure of economic inequality that runs from zero (everyone has the same income) to 100 (one person has the entire income of a country), has risen from around 35 to the low 40s in the United States, from 32 to 35 in India, from 30 to 37 in the United Kingdom, from less than 30 to 45 in both Russia and China, and from 22 to 29 in famously egalitarian Sweden. According to the OECD, during the same time frame, the Gini coefficient increased in 16 out of 20 rich countries. The situation was no different in the emerging market economies: in addition to in India and China, it rose in Indonesia, South Africa, and all the post-Communist countries.
For the poor, the gap has been palpable. In much of the world, the size of the economic pie has been shrinking, and the poor’s relative slice has been getting smaller. The poor’s actual income thus declined on two accounts. Despite large increase in global mean income between 1980 and 2005, excluding China, the number of people who live — or, rather, barely subsist — on an income below the absolute poverty line (1 dollar per day) remained constant, at 1.2 billion.