Increase In Global Surface Temperature Research Articles

Organic matter dynamics in a temperate forest soil following enhanced drying

Climate models predict an increase in global surface temperature and a change in precipitation intensity during this century. For Europe, extended drought periods followed by heavy rainfall are expected. The consequences for soil organic matter (SOM) dynamics are poorly understood. In this study, we investigated the effect of changing soil moisture regime on SOM quality under field conditions. For this purpose, a throughfall exclusion (TE) experiment was conducted in the summers 2006 and 2007 on a Haplic Podzol under a 140 years old Norway spruce stand using a roof installation followed by re-wetting compared to non-manipulated control plots. Total organic carbon, lignin (stable carbon pool), plant and microbial sugars (labile carbon pool) and microbial biomass (phospholipid fatty acids) were determined before, during and after the experiment in the L, O, A and B horizons. No significant treatment effects could be observed for SOM quantity. Amounts of lignin and soil microbial biomass were also not affected by the moisture regime but structure of soil microbial community. In the L and organic layers, gram + bacteria and actinomycetes were reduced during water stress, while gram- bacteria, fungi and protozoa increased during drought. Warmer and drier weather led to a dominance of fungi while a cooler and moister regime favoured bacteria, at least in the L horizon. An increasing PLFA (cy17:0 + cy19:0)/(16:1ω7c + 18:1ω7c) ratio in the O layer and A horizon suggests that the microbes suffered from water stress in these horizons. This agrees with a decreasing contribution of microbial sugars to SOM with decreasing water content in the O and A horizons. Although the original plant material exhibited increasing plant sugar content with increasing dryness, the contribution of the plant sugars to total soil organic carbon (SOC) generally decreased with decreasing water content. Physical-chemical changes of soil structure can theoretically change the sugar extractability from soils and/or chemical changes of sugars structure can probably affect the analysis. Therefore, chemical alteration and stabilization could be responsible for sugar decrease in soil with increasing dryness explaining the contrast compared to the original plant material.

Preparedness and storm hazards in a global warming world: lessons from Southeast Asia

The 2007 Intergovernmental Panel on Climate Change (IPCC) Assessment Report 4 found an average increase in global surface temperature of 0.74°C between 1906 and 2005. There is general agreement in the literature that the frequency of extreme precipitation events in Southeast Asia will increase with global warming. In particular, the potential impact of associated storm hazards will render the densely populated countries in Southeast Asia vulnerable to such changes in precipitation events. One main adaptation strategy given such impending changes is preparedness. Using existing literature and historical meteorological data, this paper establishes that Southeast Asia is indeed experiencing storms of higher intensities and more frequently. Two case of extreme storm event in Southeast Asia, the extreme high rainfall event in December 2006 in Southern Johor and Typhoon Vamei, are presented to consider the implications of the increased storm activities due to global warming. These two examples also discuss the need for preparedness in adapting to the impact of global warming.

Assessing the Impact of Climate Change on Long-term Energy savings with eQUEST

ABSTRACT The most recent IPCC Assessment Report (AR4, 2007) includes projections of the increase in global surface temperature attributable to increased atmospheric greenhouse gas concentrations. Any sustained increase in global surface temperatures would be expected to lead to an increase in annual space-cooling energy usage and a decrease in space-heating energy usage. In an effort to reduce energy usage and greenhouse gas emissions, many buildings are receiving energy efficiency upgrades. The HVAC related efficiency upgrades would be impacted by the expected changes in global surface temperature. Savings associated with upgrades are often determined by using building energy simulation methods, which are typically based on long-term historical weather data such as TMY data sets. This method is backward-looking in that it predicts future energy usage based on the weather data of past decades. This article examines the results of adjusting weather data to more closely match IPCC predictions on energy savi...

A Palaeogene perspective on climate sensitivity and methane hydrate instability

The Palaeocene-Eocene thermal maximum (PETM), a rapid global warming event and carbon-cycle perturbation of the early Palaeogene, provides a unique test of climate and carbon-cycle models as well as our understanding of sedimentary methane hydrate stability, albeit under conditions very different from the modern. The principal expression of the PETM in the geological record is a large and rapid negative excursion in the carbon isotopic composition of carbonates and organic matter from both marine and terrestrial environments. Palaeotemperature proxy data from across the PETM indicate a coincident increase in global surface temperatures of approximately 5-6 degrees C. Reliable estimates of atmospheric CO(2) changes and global warming through past transient climate events can provide an important test of the climate sensitivities reproduced by state-of-the-art atmosphere-ocean general circulation models. Here, we synthesize the available carbon-cycle model estimates of the magnitude of the carbon input to the ocean-atmosphere-biosphere system, and the consequent atmospheric pCO(2) perturbation, through the PETM. We also review the theoretical mass balance arguments and available sedimentary evidence for the role of massive methane hydrate dissociation in this event. The plausible range of carbon mass input, approximately 4000-7000 PgC, strongly suggests a major alternative source of carbon in addition to any contribution from methane hydrates. We find that the potential range of PETM atmospheric pCO(2) increase, combined with proxy estimates of the PETM temperature anomaly, does not necessarily imply climate sensitivities beyond the range of state-of-the-art climate models.

The climatological record of clear‐sky longwave radiation at the Earth's surface: evidence for water vapour feedback?

An increase in global surface temperature of between 1.4 K and 5.8 K is expected to occur by 2100 due to a doubling of the global concentration of CO2. Associated with this predicted surface warming will be an increase in the downwards longwave (3–100 µm) radiation (F↓) at the Earth's surface. Observations of this quantity on a global scale are almost non‐existent. Clear‐sky estimates of F↓ can be obtained from radiative transfer calculations using temperature and moisture profiles from radiosoundings. Here long‐term (more than 25 years) mean monthly profiles obtained from globally distributed land‐based radiosonde stations are subjected to detailed radiative transfer computations and Fourier time‐series analysis. The results indicate that over the period 1964–1990, there has been a global increase in the clear‐sky longwave flux at the surface. The global trend is approximately +1.7 W m−2 per decade, and there is a strong latitudinal pattern, with greater increases occurring in the tropics and smaller increases at both poles. There are also concomitant increases in precipitable water and the patterns appear to be highly correlated with increases in F↓. Increases in CO2 with time were not included in the calculations and it is estimated that the radiative impact of changes in CO2 on the F↓ trend is ∼20% per decade. A simple model of the dependence of surface air temperature and precipitable water on the downwards clear‐sky flux supports the notion that both variables are contributing to increases in F↓. It is suggested that increases in precipitable water represent a positive feedback on F↓.

Environmental precursors to rapid light carbon injection at the Palaeocene/Eocene boundary

The start of the Palaeocene/Eocene thermal maximum--a period of exceptional global warming about 55 million years ago--is marked by a prominent negative carbon isotope excursion that reflects a massive input of 13C-depleted ('light') carbon to the ocean-atmosphere system. It is often assumed that this carbon injection initiated the rapid increase in global surface temperatures and environmental change that characterize the climate perturbation, but the exact sequence of events remains uncertain. Here we present chemical and biotic records of environmental change across the Palaeocene/Eocene boundary from two sediment sections in New Jersey that have high sediment accumulation rates. We show that the onsets of environmental change (as recorded by the abundant occurrence ('acme') of the dinoflagellate cyst Apectodinium) and of surface-ocean warming (as evidenced by the palaeothermometer TEX86) preceded the light carbon injection by several thousand years. The onset of the Apectodinium acme also precedes the carbon isotope excursion in sections from the southwest Pacific Ocean and the North Sea, indicating that the early onset of environmental change was not confined to the New Jersey shelf. The lag of approximately 3,000 years between the onset of warming in New Jersey shelf waters and the carbon isotope excursion is consistent with the hypothesis that bottom water warming caused the injection of 13C-depleted carbon by triggering the dissociation of submarine methane hydrates, but the cause of the early warming remains uncertain.

CO2 threshold for millennial-scale oscillations in the climate system: implications for global warming scenarios

We present several equilibrium runs under varying atmospheric CO2 concentrations using the University of Victoria Earth System Climate Model (UVic ESCM). The model shows two very different responses: for CO2 concentrations of 400 ppm or lower, the system evolves into an equilibrium state. For CO2 concentrations of 440 ppm or higher, the system starts oscillating between a state with vigorous deep water formation in the Southern Ocean and a state with no deep water formation in the Southern Ocean. The flushing events result in a rapid increase in atmospheric temperatures, degassing of CO2 and therefore an increase in atmospheric CO2 concentrations, and a reduction of sea ice cover in the Southern Ocean. They also cool the deep ocean worldwide. After the flush, the deep ocean warms slowly again and CO2 is taken up by the ocean until the stratification becomes unstable again at high latitudes thousands of years later. The existence of a threshold in CO2 concentration which places the UVic ESCM in either an oscillating or non-oscillating state makes our results intriguing. If the UVic ESCM captures a mechanism that is present and important in the real climate system, the consequences would comprise a rapid increase in atmospheric carbon dioxide concentrations of several tens of ppm, an increase in global surface temperature of the order of 1–2°C, local temperature changes of the order of 6°C and a profound change in ocean stratification, deep water temperature and sea ice cover.

Are there connections between the Earth's magnetic field and climate?

Understanding climate change is an active topic of research. Much of the observed increase in global surface temperature over the past 150 years occurred prior to the 1940s and after the 1980s. The main causes invoked are solar variability, changes in atmospheric greenhouse gas content or sulfur due to natural or anthropogenic action, or internal variability of the coupled ocean–atmosphere system. Magnetism has seldom been invoked, and evidence for connections between climate and magnetic field variations have received little attention. We review evidence for correlations which could suggest such (causal or non-causal) connections at various time scales (recent secular variation ∼ 10–100 yr, historical and archeomagnetic change ∼ 100–5000 yr, and excursions and reversals ∼ 10 3–10 6 yr), and attempt to suggest mechanisms. Evidence for correlations, which invoke Milankovic forcing in the core, either directly or through changes in ice distribution and moments of inertia of the Earth, is still tenuous. Correlation between decadal changes in amplitude of geomagnetic variations of external origin, solar irradiance and global temperature is stronger. It suggests that solar irradiance could have been a major forcing function of climate until the mid-1980s, when “anomalous” warming becomes apparent. The most intriguing feature may be the recently proposed archeomagnetic jerks, i.e. fairly abrupt (∼ 100 yr long) geomagnetic field variations found at irregular intervals over the past few millennia, using the archeological record from Europe to the Middle East. These seem to correlate with significant climatic events in the eastern North Atlantic region. A proposed mechanism involves variations in the geometry of the geomagnetic field (f.i. tilt of the dipole to lower latitudes), resulting in enhanced cosmic-ray induced nucleation of clouds. No forcing factor, be it changes in CO 2 concentration in the atmosphere or changes in cosmic ray flux modulated by solar activity and geomagnetism, or possibly other factors, can at present be neglected or shown to be the overwhelming single driver of climate change in past centuries. Intensive data acquisition is required to further probe indications that the Earth's and Sun's magnetic fields may have significant bearing on climate change at certain time scales.

The ACPI Climate Change Simulations

The Parallel Climate Model (PCM) has been used in the Accelerated ClimatePrediction Initiative (ACPI) Program to simulate the global climateresponse to projected CO2, sulfate, and other greenhouse gasforcingunder a business-as-usual emissions scenario during the 21st century. In these runs, the oceans were initialized to 1995 conditions by a group from the Scripps Institution of Oceanography and other institutions. An ensemble of three model runs was then carried out to the year 2099 using the projected forcing. Atmospheric data fromthese runs were saved at 6-hourly intervals (hourly for certain criticalfields) to support the ACPI objective of accurately modeling hydrologicalcycles over the western U.S. It is shown that the initialization to1995 conditions partly removes the un-forced oceanic temperature and salinity drifts that occurred in the standard 20th century integration. The ACPI runs show a global surface temperature increase of 3–8 °C over northern high-latitudes by the end of the 21st century, and 1–2 °C over the oceans. This is generally within ±0.1°Cof model runs without the 1995 ocean initialization. The exception is in theAntarctic circumpolar ocean where surface air temperature is cooler in theACPI run; however the ensemble scatter is large in this region. Althoughthe difference in climate at the end of the 21st century is minimalbetween the ACPI runs and traditionally spun up runs, it might be largerfor CGCMs with higher climate sensitivity or larger ocean drifts. Ourresults suggest that the effect of small errors in the oceans (such asthose associated with climate drifts) on CGCM-simulated climate changesfor the next 50–100 years may be negligible.

Evolution of El Niño–Southern Oscillation and global atmospheric surface temperatures

The origins of the delayed increases in global surface temperature accompanying El Niño events and the implications for the role of diabatic processes in El Niño–Southern Oscillation (ENSO) are explored. The evolution of global mean surface temperatures, zonal means and fields of sea surface temperatures, land surface temperatures, precipitation, outgoing longwave radiation, vertically integrated diabatic heating and divergence of atmospheric energy transports, and ocean heat content in the Pacific is documented using correlation and regression analysis. For 1950–1998, ENSO linearly accounts for 0.06°C of global surface temperature increase. Warming events peak 3 months after SSTs in the Niño 3.4 region, somewhat less than is found in previous studies. Warming at the surface progressively extends to about ±30° latitude with lags of several months. While the development of ocean heat content anomalies resembles that of the delayed oscillator paradigm, the damping of anomalies through heat fluxes into the atmosphere introduces a substantial diabatic component to the discharge and recharge of the ocean heat content. However, most of the delayed warming outside of the tropical Pacific comes from persistent changes in atmospheric circulation forced from the tropical Pacific. A major part of the ocean heat loss to the atmosphere is through evaporation and thus is realized in the atmosphere as latent heating in precipitation, which drives teleconnections. Reduced precipitation and increased solar radiation in Australia, Southeast Asia, parts of Africa, and northern South America contribute to surface warming that peaks several months after the El Niño event. Teleconnections contribute to the extensive warming over Alaska and western Canada through a deeper Aleutian low and stronger southerly flow into these regions 0–12 months later. The 1976/1977 climate shift and the effects of two major volcanic eruptions in the past 2 decades are reflected in different evolution of ENSO events. At the surface, for 1979–1998 the warming in the central equatorial Pacific develops from the west and progresses eastward, while for 1950–1978 the anomalous warming begins along the coast of South America and spreads westward. The eastern Pacific south of the equator warms 4–8 months later for 1979–1998 but cools from 1950 to 1978.

Solar variability and climate change: Geomagnetic aa index and global surface temperature

During the past ∼120 years, Earth's surface temperature is correlated with both decadal averages and solar cycle minimum values of the geomagnetic aa index. The correlation with aa minimum values suggests the existence of a long‐term (low‐frequency) component of solar irradiance that underlies the 11‐year cyclic component. Extrapolating the aa‐temperature correlations to Maunder Minimum geomagnetic conditions implies that solar forcing can account for ∼50% or more of the estimated ∼0.7–1.5°C increase in global surface temperature since the second half of the 17th century. Our analysis is admittedly crude and ignores known contributors to climate change such as warming by anthropogenic greenhouse‐gases or cooling by volcanic aerosols. Nevertheless, the general similarity in the time‐variation of Earth's surface temperature and the low‐frequency or secular component of the aa index over the last ∼120 years supports other studies that indicate a more significant role for solar variability in climate change on decadal and century time‐scales than has previously been supposed. The most recent aa data for the current solar minimum suggest that the long‐term component of solar forcing will level off or decline during the coming solar cycle.

Outline of Health Effects of Global Climate Change

Human activities, such as combustion of fossil fuels, agricultural activities and changes in land- use, are responsible for global climate change. Because of the rapid increase of anthropogenic greenhouse gas emissions (carbon dioxide, methane and nitrous oxide), climate models predict an increase in global surface temperatures of 1.0°C to 3.5°C by the year 2100. Using general circulation models, it is estimated that surface temperatures in and around Japan will rise 1°C to 3°C during the next 100 years. Because global warming may increase the frequency and length of high temperatures during hot summer months in temperate regions, various health risks caused by heat stress have been studied. According to an epidemiological survey, the incidence of heat-related illness was significantly correlated to hot environments in Tokyo, Japan and in Nanjing and Wuhan, China. The epidemiological results showed that the incidence of heat related mortality and morbidity, such as heat stroke in the elderly, increased very rapidly when daily maximum temperatures in summer months rose above 31°C in Tokyo and 35°C in Nanjing and Wuhan, respectively. J Epidemiol, 1996 ; 6 : S141-S144.

A non‐flux corrected transient CO2 experiment using the BMRC Coupled Atmosphere/Ocean GCM

A transient CO2 experiment has been performed with the BMRC coupled atmosphere ocean General Circulation Model (GCM). No flux corrections were used in the experiment. A roughly linear temporal increase in global surface temperature is found in response to the CO2 increase. The rate of increase is consistent with the (relatively low) equilibrium response found previously using the Atmospheric GCM and a simple ocean. Ocean surface temperatures increase more at mid latitudes than at high northern or southern latitudes where heat is sequestered into the deep ocean. Despite the secular climate drift which occurs in the model, the major patterns of atmospheric and oceanic temperature change are similar to changes noted elsewhere (from flux corrected models). This adds further support to the main conclusions drawn from transient CO2 experiments performed elsewhere with coupled GCMs.

Continental drift, runoff, and weathering feedbacks: Implications from climate model experiments

Changes in atmospheric carbon dioxide have been proposed as a major regulator of climate during the last 570 million years. Continental weathering and its variation over time are hypothesized to be important for controlling atmospheric carbon dioxide. Continental weathering is altered by changes in total runoff as well as changes in the size and elevation of the land masses to be weathered. When paleogeographic information for the Phanerozoic (570 m.y. ago to present) is used in a global climate model, the model exhibits substantial variations in precipitation, evaporation, and runoff. Even with dramatically different land‐ocean distributions, an increase in global surface temperature leads to an increase in global precipitation but not always an increase in global runoff. During the early Phanerozoic (514–342 Ma), when the continents are relatively small and widely distributed, runoff depends on continental evaporation and temperature. As the continents migrate into subtropical latitudes, global runoff decreases as global land temperatures and evaporation increase. As the continents shift to higher latitudes, global runoff increases as global land temperatures and evaporation decrease. During the middle to late Phanerozoic (306 Ma‐present), when large continental land masses predominate, runoff depends on continental precipitation. Experiments with increased atmospheric CO2 for the middle Ordovician (458 Ma), when the paleocontinent of Gondwana was centered at subtropical latitudes, and the early Silurian (425 Ma), when Gondwana had shifted to middle and high latitudes, also point to a correlation between land mass location and runoff. Global runoff increases 15% with increased CO2 at 425 Ma but remains unchanged for 458 Ma, even though global mean temperature and precipitation increase comparable amounts for the two time periods. These results imply that weathering feedback between temperature and runoff may be dependent on land‐ocean configuration.

Global surface temperatures and the atmospheric electrical circuit

To monitor future global temperature trends, it would be extremely useful if parameters nonlinearly related to surface temperature could be found, thereby amplifying any warming signal that may exist. Evidence that global thunderstorm activity is nonlinearly related to diurnal, seasonal and interannual temperature variations is presented. Since global thunderstorm activity is also well correlated with the earth's ionospheric potential, it appears that variations of ionospheric potential, that can be measured at a single location, may be able to supply valuable information regarding global surface temperature fluctuations. The observations presented enable a prediction that a 1% (≈3K) increase in global surface temperatures may result in a 20% (≈50KV) increase in ionospheric potential.

A review of the carbon dioxide greenhouse problem

An enhanced “greenhouse effect” due to an increase in atmospheric CO 2 is expected to produce significant climatic changes. If the combustion of fossil fuels is the only anthropogenic source of atmospheric CO 2, measurements show that 54% resides in the atmosphere. The largest reservoir for the remaining 46% is the oceans. Known oceanic processes can account for 35% and the major uncertainty appears to be the role played by the intermediate waters. If, however, deforestation is as large a source of additional atmospheric CO 2 as some have suggested, carbon balance cannot be obtained with presently identified removal processes. Various computer models have been used to calculate the effects of increasing atmospheric CO 2. These include energy balance, radiative-convective and general circulation models (GCM's). Many feedback mechanisms must be considered including water vapour, clouds, oceans and the cryosphere. Although representing a considerable advance over other models, GCM's still require many approximations, of which the treatment of oceans and clouds are the most questionable. These models predict, for the scenario of the doubling of atmospheric CO 2, an increase in global surface temperature of about 3°C with larger increases, up to 10° at higher latitudes. Significant changes in evaporation and precipitation patterns are also indicated.

The effect of ocean heat capacity upon global warming due to increasing atmospheric carbon dioxide

Time‐dependent global warming due to increasing levels of atmospheric carbon dioxide has been estimated by employing an ocean‐land global climate model. Ocean heat capacity is incorporated by means of a global ocean model having a 70 m deep mixed layer, with heat being transported from the mixed layer to deeper waters by eddy diffusion. The time‐dependent increase in atmospheric CO2, from 1860 to 2025, is taken from carbon‐cycle models. The model results suggest that ocean heat capacity will produce a lag in CO2‐induced global warming of about 2 decades. For example, without inclusion of ocean heat capacity the model predicts that an increase in global surface temperature of 1°C, relative to 1860, will occur by 1988. But when ocean heat capacity is included, the 1°C warming is delayed until 2006–2012, this range of times corresponding to no land‐ocean advective coupling (2006) and complete land‐ocean coupling (2012). By 2025, when the assumed atmospheric CO2 content is twice the 1860 value, the model predicts global warming of 1.5°–1.8°C, in contrast to 3.1°C when ocean heat capacity is neglected.

On the Carbon Dioxide–Climate Confusion

Abstract A number of estimates of global surface temperature sensitivity to a doubling of atmospheric carbon dioxide to 600 ppm are collected here and critically reviewed. The assumptions and formulations that lead to differences between certain models' estimates are explained in some detail. Based on current understanding of climate theory and modeling it is concluded that a state-of-the-art order-of-magnitude estimate for the global surface temperature increase from a doubling of atmospheric C02 content is between 1.5 and 3 K with an amplification of the global average increase in polar zones. It is pointed out, however, that this estimate may prove to be high or low by several-fold as a result of climatic feedback mechanisms not properly accounted for in state-of-the-art models.

Corrosion of aircraft metals

Climate projections are based on emission scenarios. The emission scenarios used by the IPCC and by mainstream climate scientists are largely derived from the predicted demand for fossil fuels, and in our view take insufficient consideration of the constrained emissions that are likely due to the depletion of these fuels. This paper, by contrast, takes a supply-side view of CO2 emission, and generates two supply-driven emission scenarios based on a comprehensive investigation of likely long-term pathways of fossil fuel production drawn from peer-reviewed literature published since 2000. The potential rapid increases in the supply of the non-conventional fossil fuels are also investigated. Climate projections calculated in this paper indicate that the future atmospheric CO2 concentration will not exceed 610 ppm in this century; and that the increase in global surface temperature will be lower than 2.6 °C compared to pre-industrial level even if there is a significant increase in the production of non-conventional fossil fuels. Our results indicate therefore that the IPCC’s climate projections overestimate the upper-bound of climate change. Furthermore, this paper shows that different production pathways of fossil fuels use, and different climate models, are the two main reasons for the significant differences in current literature on the topic.