Global Warming CO2 Research Articles

THE PROBLEM OF THE DEPENDENCE OF GLOBAL WARMING ON THE INCREASE IN CO2 AS A SCIENTIFIC DEBATE

The Purpose of the Study is theoretical substantiation of the problem of global warming and climate change. The Research Methodology. Methods of analysis, modelling, description and generalization of data were used to study the problem of the dependence of global warming and climate change on the increase in CO2. The Scientific Novelty of the study consists in identifying the contradictions of scientific conclusions regarding the direct dependence of global warming and climate change on the level of CO2, outlining new directions of experimental work on the specified problem. The Conclusion. For an objective study of the climate problem and the role of CO2 in global warming, additional unbiased studies are needed, which are based on scientific facts and involve the use of the most modern measurement tools.

Attribution analysis for the failure of CMIP5 climate models to simulate the recent global warming hiatus

The Coupled Model Inter-comparison Project Phase 5 (CMIP5) contains a group of state-of-the-art climate models and represents the highest level of climate simulation thus far. However, these models significantly overestimated global mean surface temperature (GMST) during 2006–2014. Based on the ensemble empirical mode decomposition (EEMD) method, the long term change of the observed GMST time series of HadCRUT4 records during 1850–2014 was analyzed, then the simulated GMST by 33 CMIP5 climate models was assessed. The possible reason that climate models failed to project the recent global warming hiatus was revealed. Results show that during 1850–2014 the GMST on a centennial timescale rose with fluctuation, dominated by the secular trend and the multi-decadal variability (MDV). The secular trend was relatively steady beginning in the early 20th century, with an average warming rate of 0.0883°C/decade over the last 50 years. While the MDV (with a ~65-year cycle) showed 2.5 multi-decadal waves during 1850–2014, which deepened and steepened with time, the alarming warming over the last quarter of the 20th century was a result of the concurrence of the secular warming trend and the warming phase of the MDV, both of which accounted one third of the temperature increase during 1975–1998. Recently the slowdown of global warming emerged as the MDV approached its third peak, leading to a reduction in the warming rate. A comparative analysis between the GMST time series derived from HadCRUT4 records and 33 CMIP5 model outputs reveals that the GMSTs during the historical simulation period of 1850–2005 can be reproduced well by models, especially on the accelerated global warming over the last quarter of 20th century. However, the projected GMSTs and their linear trends during 2006–2014 under the RCP4.5 scenario were significantly higher than observed. This is because the CMIP5 models confused the MDV with secular trend underlying the GMST time series, which results in a fast secular trend and an improper MDV with irregular phases and small amplitudes. This implies that the role of atmospheric CO2 in global warming may be overestimated, while the MDV which is an interior oscillation of the climate system may be underestimated, which should be related to insufficient understanding of key climatic internal dynamic processes. Our study puts forward an important criterion for the new generation of climate models: they should be able to simulate both the secular trend and the MDV of GMST.

The role of CT and MRI in the diagnosis of sigmoid volvulus

Carbon dioxide (CO2) capture has attracted great interest these days due to the role of CO2 in global warming and its effects in industrial processes. Thus, higher energy efficient and affordable technologies are required for its removal so as to address these problems. In this work, the reaction kinetics of CO2 with 2-amino-2-hyroxymethyl- 1,3-propanediol (AHPD), a sterically hindered amine (SHA), was studied by direct stopped flow method. The aim was to research CO2 absorbent with better CO2 absorption capacity and reaction kinetics than the commonly applied amine solvents. The study was carried out at 288, 298, and 303 K in a concentration range of 0.5-2.0 kmol/m3 of AHPD. Based on the pseudo-first-order for the reaction of CO2, it was found that the reaction can be modeled by a single termolecular reaction mechanism. The reaction rate between CO2 and aqueous solution of AHPD was 9.99, 12.03, and 16.05 m3/kmol.s at 288, 298, and 303 K, respectively, while its activation energy was 31.59 kJ/mol. The results obtained were compared with published reaction rate data of other amines. The present study shows that AHPD is a potential SHA as CO2 absorbent if the reaction rate is enhanced by an additional amine.