scholarly journals Emergent Constraints on Climate-Carbon Cycle Feedbacks

2019 ◽  
Vol 5 (4) ◽  
pp. 275-281 ◽  
Author(s):  
Peter M. Cox
Keyword(s):  
Climate Change ◽  
Carbon Cycle ◽  
Future Climate ◽  
Future Climate Change ◽  
Climate Projections ◽  
Earth System ◽  
Model Errors ◽  
The Earth ◽  
The Future ◽  
Emergent Constraints

Abstract Purpose of Review Feedbacks between CO2-induced climate change and the carbon cycle are now routinely represented in the Earth System Models (ESMs) that are used to make projections of future climate change. The inconclusion of climate-carbon cycle feedbacks in climate projections is an important advance, but has added a significant new source of uncertainty. This review assesses the potential for emergent constraints to reduce the uncertainties associated with climate-carbon cycle feedbacks. Recent Findings The emergent constraint technique involves using the full ensemble of models to find an across-ensemble relationship between an observable feature of the Earth System (such as a trend, interannual variation or change in seasonality) and an uncertain aspect of the future. Examples focussing on reducing uncertainties in future atmospheric CO2 concentration, carbon loss from tropical land under warming and CO2 fertilization of mid- and high-latitude photosynthesis are exemplars of these different types of emergent constraints. Summary The power of emergent constraints is that they use the enduring range in model projections to reduce uncertainty in the future of the real Earth System, but there are also risks that indiscriminate data-mining, and systematic model errors could yield misleading constraints. A hypothesis-driven theory-led approach can overcome these risks and also reveal the true promise of emergent constraints—not just as ways to reduce uncertainty in future climate change but also to catalyse advances in our understanding of the Earth System.

scholarly journals Carbon cycle feedbacks and future climate change

2015 ◽  
Vol 373 (2054) ◽  
pp. 20140421 ◽  
Author(s):  
Pierre Friedlingstein
Keyword(s):  
Climate Change ◽  
Carbon Cycle ◽  
Positive Feedback ◽  
Future Climate ◽  
Future Climate Change ◽  
Earth System ◽  
System Models ◽  
New Findings ◽  
Tightly Coupled ◽  
Earth System Models

Climate and carbon cycle are tightly coupled on many timescales, from interannual to multi-millennial timescales. Observations always evidence a positive feedback, warming leading to release of carbon to the atmosphere; however, the processes at play differ depending on the timescales. State-of-the-art Earth System Models now represent these climate-carbon cycle feedbacks, always simulating a positive feedback over the twentieth and twenty-first centuries, although with substantial uncertainty. Recent studies now help to reduce this uncertainty. First, on short timescales, El Niño years record larger than average atmospheric CO 2 growth rate, with tropical land ecosystems being the main drivers. These climate-carbon cycle anomalies can be used as emerging constraint on the tropical land carbon response to future climate change. Second, centennial variability found in last millennium records can be used to constrain the overall global carbon cycle response to climatic excursions. These independent methods point to climate-carbon cycle feedback at the low-end of the Earth System Models range, indicating that these models overestimate the carbon cycle sensitivity to climate change. These new findings also help to attribute the historical land and ocean carbon sinks to increase in atmospheric CO 2 and climate change.

Are there pre-Quaternary geological analogues for a future greenhouse warming?

2011 ◽  
Vol 369 (1938) ◽  
pp. 933-956 ◽  
Author(s):  
Alan M. Haywood ◽  
Andy Ridgwell ◽  
Daniel J. Lunt ◽  
Daniel J. Hill ◽  
Matthew J. Pound ◽  
...  
Keyword(s):  
Climate Change ◽  
Greenhouse Gases ◽  
Future Climate ◽  
Future Climate Change ◽  
Anthropogenic Emissions ◽  
Earth System ◽  
System Sensitivity ◽  
Earth History ◽  
Scientific Papers

Given the inherent uncertainties in predicting how climate and environments will respond to anthropogenic emissions of greenhouse gases, it would be beneficial to society if science could identify geological analogues to the human race’s current grand climate experiment . This has been a focus of the geological and palaeoclimate communities over the last 30 years, with many scientific papers claiming that intervals in Earth history can be used as an analogue for future climate change. Using a coupled ocean–atmosphere modelling approach, we test this assertion for the most probable pre-Quaternary candidates of the last 100 million years: the Mid- and Late Cretaceous, the Palaeocene–Eocene Thermal Maximum (PETM), the Early Eocene, as well as warm intervals within the Miocene and Pliocene epochs. These intervals fail as true direct analogues since they either represent equilibrium climate states to a long-term CO 2 forcing—whereas anthropogenic emissions of greenhouse gases provide a progressive (transient) forcing on climate—or the sensitivity of the climate system itself to CO 2 was different. While no close geological analogue exists, past warm intervals in Earth history provide a unique opportunity to investigate processes that operated during warm (high CO 2 ) climate states. Palaeoclimate and environmental reconstruction/modelling are facilitating the assessment and calculation of the response of global temperatures to increasing CO 2 concentrations in the longer term (multiple centuries); this is now referred to as the Earth System Sensitivity, which is critical in identifying CO 2 thresholds in the atmosphere that must not be crossed to avoid dangerous levels of climate change in the long term. Palaeoclimatology also provides a unique and independent way to evaluate the qualities of climate and Earth system models used to predict future climate.

scholarly journals An evaluation of the effect of future climate on runoff in the Dongjiang River basin, South China

2015 ◽  
Vol 368 ◽  
pp. 257-262
Author(s):  
K. Lin ◽  
W. Zhai ◽  
S. Huang ◽  
Z. Liu
Keyword(s):  
Climate Change ◽  
River Basin ◽  
South China ◽  
Annual Runoff ◽  
Future Climate ◽  
Weather Data ◽  
Future Climate Change ◽  
Dongjiang River ◽  
The Future ◽  
The Impact

Abstract. The impact of future climate change on the runoff for the Dongjiang River basin, South China, has been investigated with the Soil and Water Assessment Tool (SWAT). First, the SWAT model was applied in the three sub-basins of the Dongjiang River basin, and calibrated for the period of 1970–1975, and validated for the period of 1976–1985. Then the hydrological response under climate change and land use scenario in the next 40 years (2011–2050) was studied. The future weather data was generated by using the weather generators of SWAT, based on the trend of the observed data series (1966–2005). The results showed that under the future climate change and LUCC scenario, the annual runoff of the three sub-basins all decreased. Its impacts on annual runoff were –6.87%, –6.54%, and –18.16% for the Shuntian, Lantang, and Yuecheng sub-basins respectively, compared with the baseline period 1966–2005. The results of this study could be a reference for regional water resources management since Dongjiang River provides crucial water supplies to Guangdong Province and the District of Hong Kong in China.

scholarly journals Including Variability across Climate Change Projections in Assessing Impacts on Water Resources in an Intensively Managed Landscape

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 286
Author(s):  
Bangshuai Han ◽  
Shawn G. Benner ◽  
Alejandro N. Flores
Keyword(s):  
Climate Change ◽  
Future Climate ◽  
Coupled Processes ◽  
Future Climate Change ◽  
Irrigated Agriculture ◽  
Climate Projections ◽  
Climate Scenarios ◽  
Irrigation Amount ◽  
Stochastic Weather Generator ◽  
Intensively Managed

：In intensively managed watersheds, water scarcity is a product of interactions between complex biophysical processes and human activities. Understanding how intensively managed watersheds respond to climate change requires modeling these coupled processes. One challenge in assessing the response of these watersheds to climate change lies in adequately capturing the trends and variability of future climates. Here we combine a stochastic weather generator together with future projections of climate change to efficiently create a large ensemble of daily weather for three climate scenarios, reflecting recent past and two future climate scenarios. With a previously developed model that captures rainfall-runoff processes and the redistribution of water according to declared water rights, we use these large ensembles to evaluate how future climate change may impact satisfied and unsatisfied irrigation throughout the study area, the Treasure Valley in Southwest Idaho, USA. The numerical experiments quantify the changing rate of allocated and unsatisfied irrigation amount and reveal that the projected temperature increase more significantly influences allocated and unsatisfied irrigation amounts than precipitation changes. The scenarios identify spatially distinct regions in the study area that are at greater risk of the occurrence of unsatisfied irrigation. This study demonstrates how combining stochastic weather generators and future climate projections can support efforts to assess future risks of negative water resource outcomes. It also allows identification of regions in the study area that may be less suitable for irrigated agriculture in future decades, potentially benefiting planners and managers.

scholarly journals Amplified Arctic warming by phytoplankton under greenhouse warming

2015 ◽  
Vol 112 (19) ◽  
pp. 5921-5926 ◽  
Author(s):  
Jong-Yeon Park ◽  
Jong-Seong Kug ◽  
Jürgen Bader ◽  
Rebecca Rolph ◽  
Minho Kwon
Keyword(s):  
Ecosystem Model ◽  
Future Climate ◽  
Marine Phytoplankton ◽  
The Arctic ◽  
Future Climate Change ◽  
Greenhouse Warming ◽  
Climate Projections ◽  
Arctic Warming ◽  
Marine Ecosystem Model ◽  
The Future

Phytoplankton have attracted increasing attention in climate science due to their impacts on climate systems. A new generation of climate models can now provide estimates of future climate change, considering the biological feedbacks through the development of the coupled physical–ecosystem model. Here we present the geophysical impact of phytoplankton, which is often overlooked in future climate projections. A suite of future warming experiments using a fully coupled ocean−atmosphere model that interacts with a marine ecosystem model reveals that the future phytoplankton change influenced by greenhouse warming can amplify Arctic surface warming considerably. The warming-induced sea ice melting and the corresponding increase in shortwave radiation penetrating into the ocean both result in a longer phytoplankton growing season in the Arctic. In turn, the increase in Arctic phytoplankton warms the ocean surface layer through direct biological heating, triggering additional positive feedbacks in the Arctic, and consequently intensifying the Arctic warming further. Our results establish the presence of marine phytoplankton as an important potential driver of the future Arctic climate changes.

Environmental Security and Climate Change

2010 ◽  
Author(s):  
Simon Dalby
Keyword(s):  
Climate Change ◽  
Environmental Change ◽  
Security Policy ◽  
Growth Failure ◽  
Environmental Security ◽  
Peace Building ◽  
Future Climate Change ◽  
Fragile States ◽  
Earth System ◽  
The Earth

Environmental security focuses on the ecological conditions necessary for sustainable development. It encompasses discussions of the relationships between environmental change and conflict as well as the larger global policy issues linking resources and international relations to the necessity for doing both development and security differently. Climate change has become an increasingly important part of the discussion as its consequences have become increasingly clear. What is not at all clear is in what circumstances climate change may turn out to be threat multiplier leading to conflict. Earth system science findings and the recognition of the scale of human transformations of nature in what is understood in the 21st century to be a new geological epoch, the Anthropocene, now require environmental security to be thought of in terms of preventing the worst dangers of fragile states being unable to cope with the stresses caused by rapid environmental change or perhaps the economic disruptions caused by necessary transitions to a post fossil fueled economic system. But so far, at least, this focus on avoiding the worst consequences of future climate change has not displaced traditional policies of energy security that primarily ensure supplies of fossil fuels to power economic growth. Failure to make this transition will lead to further rapid disruptions of climate and add impetus to proposals to artificially intervene in the earth system using geoengineering techniques, which might in turn generate further conflicts from states with different interests in how the earth system is shaped in future. While the Paris Agreement on Climate Change recognized the urgency of tackling climate change, the topic has not become security policy priority for most states, nor yet for the United Nations, despite numerous policy efforts to securitize climate change and instigate emergency responses to deal with the issue. More optimistic interpretations of the future suggest possibilities of using environmental actions to facilitate peace building and a more constructive approach to shaping earth’s future.

scholarly journals Past climates inform our future

Science ◽  
2020 ◽  
Vol 370 (6517) ◽  
pp. eaay3701
Author(s):  
Jessica E. Tierney ◽  
Christopher J. Poulsen ◽  
Isabel P. Montañez ◽  
Tripti Bhattacharya ◽  
Ran Feng ◽  
...  
Keyword(s):  
Climate Change ◽  
Carbon Dioxide ◽  
Model Evaluation ◽  
Future Climate Change ◽  
Earth System ◽  
High Carbon ◽  
The Earth ◽  
The World ◽  
Earth System Models ◽  
High Carbon Dioxide

As the world warms, there is a profound need to improve projections of climate change. Although the latest Earth system models offer an unprecedented number of features, fundamental uncertainties continue to cloud our view of the future. Past climates provide the only opportunity to observe how the Earth system responds to high carbon dioxide, underlining a fundamental role for paleoclimatology in constraining future climate change. Here, we review the relevancy of paleoclimate information for climate prediction and discuss the prospects for emerging methodologies to further insights gained from past climates. Advances in proxy methods and interpretations pave the way for the use of past climates for model evaluation—a practice that we argue should be widely adopted.

scholarly journals Caring for the future: Climate change and intergenerational responsibility in China and the UK

Geoforum ◽  
2019 ◽  
Vol 105 ◽  
pp. 158-167 ◽  
Author(s):  
Kristina Diprose ◽  
Chen Liu ◽  
Gill Valentine ◽  
Robert M. Vanderbeck ◽  
Katie McQuaid
Keyword(s):  
Climate Change ◽  
Future Climate ◽  
Future Climate Change ◽  
The Future ◽  
The Uk
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