Abstract: Predicting responses of coastal ecosystems to altered sea surface temperatures (SST) associated with global climate change, requires knowledge of demographic responses of individual species. Body size is an excellent metric because it scales strongly with growth and fecundity for many ectotherms. These attributes can underpin demographic as well as community and ecosystem level processes, providing valuable insights for responses of vulnerable coastal ecosystems to changing climate.
We investigated contemporary macroscale patterns in body size among widely distributed crustaceans that comprise the majority of intertidal abundance and biomass of sandy beach ecosystems of the eastern Pacific coasts of Chile and California, USA…..
Significant latitudinal patterns in body sizes were observed for all species in Chile (21° – 42°S), with similar but steeper patterns in Emerita analoga, in California (32°- 41°N). Sea surface temperature was a strong predictor of body size (-4% to -35% °C-1) in all species. Beach characteristics were subsidiary predictors of body size. Alterations in ocean temperatures of even a few degrees associated with global climate change are likely to affect body sizes of important intertidal ectotherms, with consequences for population demography, life history, community structure, trophic interactions, food-webs, and indirect effects such as ecosystem function. The consistency of results for body size and temperature across species with different life histories, feeding modes, ecological roles, and microhabitats inhabiting a single widespread coastal ecosystem, and for one species, across hemispheres in this space-for-time substitution, suggests predictions of ecosystem responses to thermal effects of climate change may potentially be generalised, with important implications for coastal conservation.
Increasing water temperatures are responsible for the accumulation of a chemical called nitrite in marine environments throughout the world, a symptom of broader changes in normal ocean biochemical pathways that could ultimately disrupt ocean food webs.
Nitrite is produced when microorganisms consume ammonium in waste products from fertilizers, treated sewage and animal waste. Too much nitrite can alter the kinds and amounts of single-celled plants living in marine environments, potentially affecting the animals that feed on them, said James Hollibaugh, co-author of the study published recently in Environmental Science and Technology. It also could lead to toxic algal blooms and create dead zones where no fish or animals can live.
“Typically, two groups of microorganisms work in really close concert with one another to convert ammonium to nitrate so that you don’t see nitrite really accumulate at all, but we found that the activity of those two groups was decoupled as a result of the increased water temperatures.”
…Nitrite accumulation can also result in more production of nitrous oxide, a powerful greenhouse gas that has more of an effect on climate change per molecule than carbon dioxide, Hollibaugh said. That nitrous oxide production then increases global temperatures more, causing more nitrite accumulation and creating a positive feedback loop.
Sylvia C. Schaefer, James T. Hollibaugh. Temperature Decouples Ammonium and Nitrite Oxidation in Coastal Waters. Environmental Science & Technology, 2017; 51 (6): 3157 DOI: 10.1021/acs.est.6b03483
THE MEASURED warming of the planet is not hypothetical. Nor are its effects, which are happening now, not decades from now. An ecological catastrophe is unfolding off Australia’s coast: Humans are killing the Great Barrier Reef, one of the world’s greatest natural wonders, and there’s nothing Australians on their own can do about it. We are all responsible.
An ocean water temperature spike last year caused a massive “bleaching” event, in which colorful corals turned an antiseptic, sickly white. Scientists believe that the reef will never be the same.
“The chances of the northern Great Barrier Reef returning to its pre-bleaching assemblage structure are slim given the scale of damage that occurred in 2016 and the likelihood of a fourth bleaching event occurring within the next decade or two as global temperatures continue to rise,” a major new study in the journal Nature reported last week….
….Alarmingly, but perhaps not surprisingly, the Australian government reports that sections of the reef are getting slammed again this year….
…There is little doubt that temperature is the culprit. Reefs far away from human runoff and other local risks are suffering. Corals in pristine water bleached just like those in dirty water. The Nature study quantified a relationship between exposure to warm water and the severity of observed bleaching.
“Immediate global action to curb future warming is essential to secure a future for coral reefs,” the study warned. “Water quality and fishing pressure had minimal effect on the unprecedented bleaching in 2016, suggesting that local protection of reefs affords little or no resistance to extreme heat. Similarly, past exposure to bleaching in 1998 and 2002 did not lessen the severity of bleaching in 2016.”…
New research has convincingly quantified how much the Earth has warmed over the past 56 years. Human activities utilize fossil fuels for many beneficial purposes but have an undesirable side effect of adding carbon dioxide to the atmosphere at ever-increasing rates. That increase – of over 40%, with most since 1980 – traps heat in the Earth’s system, warming the entire planet….
…Since about 2005 a new type of sensing device has been deployed (the Argo float system). These floats (approximately 3500 in total at any time) are spread out across oceans where they autonomously rise and fall in the ocean waters, collecting temperature data to depths of 2000 meters. When they rise to the ocean surface, they send their data wirelessly to satellites for later analysis. Hence we can now map the ocean heat content quite well…
…a paper just published today in Science Advances uses a new strategy to improve upon our understanding of ocean heating to estimate the total global warming from 1960 to 2015….shows we are warming about 13% faster than we previously thought. Not only that but the warming has accelerated. The warming rate from 1992 is almost twice as great as the warming rate from 1960. Moreover, it is only since about 1990 that the warming has penetrated to depths below about 700 meters….
Joe Romm September 14, 2016 climateprogress.org https://thinkprogress.org/global-warming-jump-419da72c9215#.9z3u2swuu
NASA temperature analysis for August: “Another month, another record.” Credit: NASA
We appear to be in the midst of the long-awaited jump in global temperatures. And that means “The kinds of extreme weather we have seen over the past year or so will be routine all too soon, but then even worse records will be set,” as Kevin Trenberth, one of the world’s leading climatologists, told me. NASA has reported that last month was not merely “the warmest August in 136 years of modern record-keeping,” it tied with this July 2016 for the “warmest month ever recorded.” And for 11 straight months (starting October 2015), the world has set a new monthly record for high temperature. So even though 2014 set the record at the time for the hottest year — and then 2015 crushed that record, NASA says there is a greater than 99 percent chance 2016 will top 2015. And it probably won’t be close according to this projection tweeted out by NASA’s Gavin Schmidt:
Land and ocean temperature index (LITI) with 2016 prediction. Credit: NASA
Why does this string of record-setting months and years matter? As I reported last year, climatologists have been expecting a “jump” in global temperatures. There is “a vast and growing body of research,” as Climate Central explained in February 2015 that “humanity is about to experience a historically unprecedented spike in temperatures.”
A March 2015 study, “Near-term acceleration in the rate of temperature change,” makes clear that an actual acceleration in the rate of global warming is imminent — with Arctic warming rising a stunning 1°F per decade by the 2020s. More than 90 percent of global heating goes into the oceans (see excellent article here) — and ocean warming has accelerated in recent years. Climatologist Kevin Trenberth of the National Center for Atmospheric Research explained here in 2013 that “a global temperature increase occurs in the latter stages of an El Niño event, as heat comes out of the ocean and warms the atmosphere.” Well, we are indeed at the end of an El Niño event, and we have indeed seen a big global temperature increase. In April 2015, Trenberth told me thought “a jump is imminent.”
Previously he had explained that this jump could be 0.2°C or 0.3°C, which is to say up to 0.5°F! That change would happen “relatively abruptly,” but last for 5 or 10 years before it jumped again. It looks like Trenberth was right (though it will take a few years to know for sure). When I asked him to comment on the stunning jump in global temperatures we’ve seen in the last 18 months, he said: “The increase in carbon dioxide and other heat trapping gases from human activities is relentless. The effects on global mean surface temperatures can be masked by natural variability for a decade or a bit more, but as the natural variability goes in the other direction, suddenly it is quite a different story and record after record gets broken.”
That’s where we are. Global temperatures often jump over a couple years, then they rise more slowly, like a staircase (or ladder) where the steps are sloped up. The climate science deniers make a lot of noise during the short periods of slower warming, and stay strangely quiet during the jumps. Go figure!
Trenberth explains that “the nature of the changes going on now suggest that we have made another step up the ladder to another rung, and we won’t go down again.” That means the recent bouts of extreme weather “will be routine all too soon, but then even worse records will be set. It is not something to welcome and it is hard to plan for.” It is time to slash carbon pollution so we can stop climbing this stairway of ever-worsening extreme weather and climate change.