Significance: Most current cost−benefit analyses of climate change suggest global climate policy should be relatively weak. However, relatively few studies account for the market or nonmarket impacts of passing environmental tipping points that cause abrupt and irreversible damages. We use a stochastic dynamic model of the climate and economy to quantify the effect of tipping points on climate change policy. We show that environmental tipping points can profoundly alter cost−benefit analysis, justifying a much more stringent climate policy, which takes the form of a higher immediate price on carbon.

We examine seasonal and geographical distributions of tropospheric ozone production and mixing ratios over East Asia with a global three‐dimensional chemical transport model called Model of Ozone and Related Tracers, version 1 (MOZART 1). Net ozone production within the East Asian boundary layer exhibits three distinct seasonal cycles depending on region (north of 20°N, 5–20°N and south of 5°N). North of 20°N, net ozone production over East Asia from spring through autumn is found to have a maximum extending from 25°N–40°N and from central eastern China to Japan, resulting from the strong emission and transport of anthropogenic O₃ precursors. In winter, maximum O₃ production in this region occurs between 20°N and 30°N. This is a region of long‐range transport. Over the Indochina peninsula, between 5°N and 20°N, net O₃ production is controlled by the seasonal cycle between wet and dry seasons and has a maximum at the end of the dry season due to emissions from biomass burning. South of 5°N, in the true tropics, O₃ mixing ratios are relatively constant throughout the year and do not exhibit a seasonal cycle. A spring‐summer maximum of net O₃ production is found throughout the troposphere in East Asia. We estimate an annual net O₃ production in East Asia of 117 Tg/yr. Both model results and analysis of measurements of O₃/CO correlations over East Asia and Japan show strong variability as a function of both photochemical activity and seasonal meteorology, and indicate ozone export off the coast of East Asia in spring. An upper estimate of O₃ export from East Asia to the Pacific Ocean in the mid‐1980s of 3.3 Gmol/d (58 Tg/yr) is obtained.

Air pollution is becoming a prominent social problem in fast-growing Asian economies. Taking the Bangkok Metropolitan Region (BMR) as a case, we conducted an observational study of fine particulate matter (PM_2.5) and acid deposition, consisting of their continuous monitoring at two sites. To find the major contributing sources of PM_2.5, the PM composition data were analyzed by a receptor modeling approach while the pollution load from BMR sources to the air was characterized by an emission inventory. Our data show generally alarming levels of PM_2.5 in the region, of which transportation and biomass burning are two major sources. In this paper, we present a general overview of our observational findings, contrast the scientific information with the policy context of air quality management in BMR, and discuss policy implications. In BMR, where a set of conventional regulatory instruments on air quality management are already in place, a solution for the air pollution problem should lie in a combination of air quality regulation and other policies, such as energy and agricultural policies.