Slowdown In Trend Research Articles

Synchronized slowdown of climate warming and carbon sink enhancement over deciduous broadleaf forests based on FLUXNET analysis

The temperate deciduous broadleaf forests (DBFs) are widely distributed in middle and high latitudes and play vital role in providing ecosystem services and mitigating human induced climate change, however, the responses of the carbon sink of DBFs to recent warming slowdown were not well known at regional scale. Here, we investigated the temporal pattern of carbon sink in DBFs and its drivers based on the eddy covariance carbon flux observations at 15 FLUXNET sites from 1997 to 2014. The annual mean net ecosystem production (NEP) was 272 ± 43 g C m−2 yr−1 during 1997–2005 and it increased to 445 ± 13 g C m−2 yr−1 during 2006–2014, as a result of boosted gross primary production (GPP) and weakened ecosystem respiration, respectively. We found slowdown in trends of temperature and carbon sink enhancement during 2006–2014. The NEP decreased at the rate of −11.9 g C m−2 yr−1 during the warming slowdown period (2006–2014, p < 0.05) compared to a prior strong increased trend during the warming period (1997–2005, 47.6 g C m−2 yr−1, p < 0.05). The mean annual temperature dominated the inter-annual variation of NEP (46.9 %), and it worked together with seasonal water availability to control the NEP changes. The slowdown of peak photosynthesis growth rate and carbon uptake period (CUP) extension may contribute to the NEP reversal during the later period. Our results demonstrated that the carbon uptake potential of temperate DBFs may highly depend on warming trends.

Addressing on Abrupt Global Warming, Warming Trend Slowdown and Related Features in Recent Decades

The puzzle of recent global warming trend slowdown has captured enough attention, though the underlying cause is still unexplained. This study addresses that area segregating the role of natural factors (the sun and volcano) to that from CO2 led linear anthropogenic contributions. It separates out a period 1976–1996 that covers two full solar cycles, where two explosive volcanos erupted during active phases of strong solar cycles. The similar period also matched the duration of abrupt global warming. It identifies that dominance of Central Pacific (CP) ENSO and associated water vapour feedback during that period play an important role. The possible mechanism could be initiated via a preferential alignment of NAO phase, generated by explosive volcanos. Inciting extratropical Rossby wave to influence the Aleutian Low, it has a modulating effect on CP ENSO. Disruption of Indian Summer Monsoon and ENSO teleconnection during the abrupt warming period and a subsequent recovery thereafter can also be explained from that angle. Interestingly, CMIP5 model ensemble, and also individual models, fails to comply with such observation. It also explores possible areas where models miss important contributions due to natural drivers.

The atmospheric electrical index for ENSO modoki: Is ENSO modoki one of the factors responsible for the warming trend slowdown?

Like the southern oscillation index (SOI) based on the pressure difference between Tahiti (17.5°S, 150°W) and Darwin (12.5°S, 130°E), we propose the new atmospheric electrical index (AEI) taking the difference in the model calculated atmospheric electrical columnar resistance (Rc) which involves planetary boundary layer height (PBLH) and aerosol concentration derived from the satellite measurements. This is the first non-oceanic index capable of differentiating between the conventional and modoki La Niña and El Niño both and may be useful in the future air-sea coupling studies and as a complementary to the oceanic indices. As the PBLH variation over Darwin is within 10% of its long term mean, a strong rise in the Rc over Darwin during the modoki period supports modoki’s connection with aerosol loading. Our correlation results show that the intensity of El Niño (La Niña) event is almost independent (not independent) of its duration and the possibility of ENSO modoki being one of the factors responsible for the warming trend slowdown (WTS).

The role of dynamically induced variability in the recent warming trend slowdown over the Northern Hemisphere.

Since the slowing of the trend of increasing surface air temperature (SAT) in the late 1990 s, intense interest and debate have arisen concerning the contribution of human activities to the warming observed in previous decades. Although several explanations have been proposed for the warming-trend slowdown (WTS), none has been generally accepted. We investigate the WTS using a recently developed methodology that can successfully identify and separate the dynamically induced and radiatively forced SAT changes from raw SAT data. The dynamically induced SAT changes exhibited an obvious cooling effect relative to the warming effect of the adjusted SAT in the hiatus process. A correlation analysis suggests that the changes are dominated primarily by the North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), and Atlantic Multidecadal Oscillation (AMO). Our results confirm that dynamically induced variability caused the WTS. The radiatively forced SAT changes are determined mainly by anthropogenic forcing, indicating the warming influence of greenhouse gases (GHGs), which reached levels of 400 ppm during the hiatus period. Therefore, the global SAT will not remain permanently neutral. The increased radiatively forced SAT will be amplified by increased dynamically induced SAT when the natural mode returns to a warming phase in the next period.

Surf Shoaling and Breaking on Two-Slope Flume Experiments

A flume experiment is carried out to explore regular waves shoaling and breaking in surf zone. The topography is two-slope model, which is composed of a steep slope 1:5 and a gentle slope 1:40. The incidence waves have heights of 0.05, 0.06, 0.07, 0.08, 0.09 and 0.10 m, and periods of 1.0 sec. In order to describe the wave propagation in surf zone, wave height is collected by wave gauges and wave breaking is recorded by high-speed camera. The results show that, when incidence height is increased, the breaking height increases, while the location of breaking point moves forward. When the incidence height is larger enough, the trend slow down. Besides, secondary breakup is observed in case 0.08, 0.09 and 0.10m. The transient period from primary breakup to secondary breakup is a very important phase. Computing and forecasting methods of surf with complicated topography need further study.

Is Malaysia Facing Negative Deindustrialization?

This paper seeks to examine whether Malaysia is facing negative deindustrialization by examining value-added, trade and productivity trends over the period 1990-2005. The evidence produced in the paper is concrete enough to confirm that Malaysia is facing negative deindustrialization. While it is typical, as part of the process of structural change, to see a rise and fall in the share occupied by manufacturing in the GDP, the evidence shows that Malaysia is indeed facing premature deindustrialization with a trend slowdown in manufacturing value-added, trade performance and productivity since 2000. Not only has the trade performance of manufacturing been falling, manufacturing labour productivity has also slowed down, with the key sectors such as electric-electronics, textiles and transport equipment showing either negative or low productivity growth since 2000. Malaysian industrial policies have been fairly successful in connecting with the global value chains of multinationals and in developing resource-based industries, but have not achieved the same success in stimulating their transformation to high value-added activities. The lack of effective institutional change, partly explained by ethnic policies, is advanced as the prime reason for the setting in of negative deindustrialization in Malaysia.

Search for evidence of trend slow-down in the long-term TOMS/SBUV total ozone data record: the importance of instrument drift uncertainty

Abstract. We have developed a merged ozone data set (MOD) for the period October 1978 through June 2006 combining total ozone measurements (Version 8 retrieval) from the TOMS (Nimbus 7, Earth Probe) and SBUV/SBUV2 (Nimbus 7, NOAA 9/11/16) series of satellite instruments. We use the MOD data set to search for evidence of ozone recovery in response to the observed leveling off of chlorine and bromine compounds in the stratosphere. A crucial step in any time series analysis is the evaluation of uncertainties. In addition to the standard statistical time series uncertainties, we evaluate the possible instrument drift uncertainty for the MOD data set. We combine these two sources of uncertainty and apply them to a cumulative sum of residuals (CUSUM) analysis for trend slow-down. For the extra-polar mean between 60° S and 60° N, the apparent slow-down in trend is found to be clearly significant if instrument uncertainties are ignored. When instrument uncertainties are added, the slow-down becomes marginally significant at the 2σ level. For the mid-latitudes of the northern hemisphere (30° to 60° N) the trend slow-down is highly significant at the 2σ level, while in the southern hemisphere the trend slow-down has yet to meet the 2σ significance criterion. The rate of change of chlorine/bromine compounds is similar in both hemispheres, and we expect the ozone response to be similar in both hemispheres as well. The asymmetry in the trend slow-down between hemispheres likely reflects the influence of dynamical variability, and thus a clearly statistically significant response of total ozone to the leveling off of chlorine and bromine in the stratosphere is not yet indicated.

Is there still a productivity paradox? two methods for a transatlantic comparison

Economic activity accelerated in the United States, in the second part of the cycle, after 1995, within an environment of decreasing inflation. France has followed a qualitatively similar path since 1997, also clearly suggesting the effects of a positive supply shock. The spread of new information and communication technologies (NICT) partly explains these singular events. On one hand, a calculation of contributions to output growth suggests that they would explain about half of the increase in activity in the United States and one-fifth in France. On the other hand, a trend/cycle decomposition reveals that the structural acceleration in output and productivity gains in the United States are very much restricted to industries producing NICT and there is a rather small break in productivity gains. In France, where differences between sectors are not so clear-cut, the diffusion of NICT has been accompanied by a slowdown in trends in productivity gains. In both cases, there is little room left for the effects of the diffusion of technical progress associated with NICT.