[1] Calcification rates in stony corals are expected to decline significantly in the near future due to ocean acidification. In this study we provide a global estimate of the decline in calcification of coral reefs as a result of increase in sea surface temperature and partial pressure of CO 2 . This estimate, unlike previously reported estimates, is based on an empirical rate law developed from field observations for gross community calcification as a function of aragonite degree of saturation (W arag ), sea surface temperature and live coral cover. Calcification rates were calculated for more than 9,000 reef locations using model values of W arag and sea surface temperature at different levels of atmospheric CO 2 . The maps we produced show that by the time atmospheric partial pressure of CO 2 will reach 560 ppm all coral reefs will cease to grow and start to dissolve. [2] The sharp anthropogenic increase in atmospheric CO 2 has changed the carbonate chemistry of the surface oceans [Sabine et al., 2004]. Model estimates suggest that the average surface ocean pH has decreased by 0.1 units relative to its pre-industrial revolution (PIR) value and it is expected to decrease by an additional 0.4 units by the close of the 21st century [Caldeira and Wickett, 2003]. Such a drop in pH at constant total alkalinity will decrease the aragonite degree of saturation (W arag ), which may lower the biogenic precipitation rate of aragonite (the carbonate mineral deposited by reef building corals) in the ocean [Kleypas et al., 1999;Orr et al., 2005] Where, the rate constant (k T ) and the order of the reaction (n T ) change as a function of temperature according to the empirical relations reported by Burton and Walter [1987]. The rate constant (k T ) has units of mmol Á m À2 Á hr À1, which are converted to units of mmol Á m À2 Á day À1 by multiplying the value of k T by 24 (hours per day) and dividing by 1000 (mmol per mmol). Application of this rate law for coral reefs includes the horizontal area fraction of the reef actively depositing CaCO 3 , i.e., percentage of live coral cover in decimal fraction equivalent (A c = 0 -1) multiplied by a specific area constant (k 0 r ). This constant (k 0 r ) is the ratio between the total area of the reef actively precipitating CaCO 3 and its planar area (i.e., m 2 /m 2 ) for a reef with 100% live coral cover (A c = 1). An additional term in the modified equation for coral reefs is the rate of community CaCO 3 dissolution (D). The modified rate law is therefore:Where the gross calcification is defined as:The linear fit between the measured and calculated net calcification for the Eilat reef yielded a slope of A c Á k . The D estimated from the correlation value is similar to the average dissolution rate measured in situ on the Eilat reef (13 ± 7 mmol Á m À2 Á day À1

[1] In this study we investigated the relations between community calcification of an entire coral reef in the northern Red Sea and annual changes in temperature, aragonite saturation and nutrient loading over a two year period. Summer (April-October) and winter (November-March) average calcification rates varied between 60 ± 20 and 30 ± 20 mmolÁm À2 Ád À1 , respectively. In general, calcification increased with temperature and aragonite saturation state of reef water with an apparent effect of nutrients, which is in agreement with most laboratory studies and in situ measurements of single coral growth rates. The calcification rates we measured in the reef correlated remarkably well with precipitation rates of inorganic aragonite calculated for the same temperature and degree of saturation ranges using empirical equations from the literature. This is a very significant finding considering that only a minute portion of reef calcification is inorganic. Hence, these relations could be used to predict the response of coral reefs to ocean acidification and warming.Citation: Silverman, J., B. Lazar, and J. Erez (2007), Effect of aragonite saturation, temperature, and nutrients on the community calcification rate of a coral reef,

Many global environmental agendas, including halting biodiversity loss, reversing land degradation, and limiting climate change, depend upon retaining forests with high ecological integrity, yet the scale and degree of forest modification remain poorly quantified and mapped. By integrating data on observed and inferred human pressures and an index of lost connectivity, we generate a globally consistent, continuous index of forest condition as determined by the degree of anthropogenic modification. Globally, only 17.4 million km2 of forest (40.5%) has high landscape-level integrity (mostly found in Canada, Russia, the Amazon, Central Africa, and New Guinea) and only 27% of this area is found in nationally designated protected areas. Of the forest inside protected areas, only 56% has high landscape-level integrity. Ambitious policies that prioritize the retention of forest integrity, especially in the most intact areas, are now urgently needed alongside current efforts aimed at halting deforestation and restoring the integrity of forests globally.

Approximately one-quarter of the anthropogenic carbon dioxide released into the atmosphere each year is absorbed by the global oceans, causing measurable declines in surface ocean pH, carbonate ion concentration ([CO3(2-)]), and saturation state of carbonate minerals (Ω). This process, referred to as ocean acidification, represents a major threat to marine ecosystems, in particular marine calcifiers such as oysters, crabs, and corals. Laboratory and field studies have shown that calcification rates of many organisms decrease with declining pH, [CO3(2-)], and Ω. Coral reefs are widely regarded as one of the most vulnerable marine ecosystems to ocean acidification, in part because the very architecture of the ecosystem is reliant on carbonate-secreting organisms. Acidification-induced reductions in calcification are projected to shift coral reefs from a state of net accretion to one of net dissolution this century. While retrospective studies show large-scale declines in coral, and community, calcification over recent decades, determining the contribution of ocean acidification to these changes is difficult, if not impossible, owing to the confounding effects of other environmental factors such as temperature. Here we quantify the net calcification response of a coral reef flat to alkalinity enrichment, and show that, when ocean chemistry is restored closer to pre-industrial conditions, net community calcification increases. In providing results from the first seawater chemistry manipulation experiment of a natural coral reef community, we provide evidence that net community calcification is depressed compared with values expected for pre-industrial conditions, indicating that ocean acidification may already be impairing coral reef growth.