Changes in the Response of the Northern Hemisphere Carbon Uptake to Temperature Over the Last Three Decades

Abstract. Tropospheric ozone and nitrogen deposition affect vegetation growth and thus the ability of the land biosphere to store carbon. However, the magnitude of this effect on the contemporary and future terrestrial carbon balance is insufficiently understood. Here, we apply an extended version of the O-CN terrestrial biosphere model that simulates the atmosphere to canopy transport of O3, its surface and stomatal uptake, as well as the ozone-induced leaf injury. We use this model to simulate past and future impacts of air pollution (ozone and nitrogen deposition) against a background of concurrent changes in climate and carbon dioxide concentrations (CO2) for two contrasting representative concentration pathways (RCP) scenarios (RCP2.6 and RCP8.5). The simulations show that O3-related damage considerably reduced Northern hemispheric gross primary production (GPP) and long-term carbon storage between 1850 and the 2010s. The ozone effect on GPP in the Northern hemisphere peaks at the end of the 20th century with reductions of 4 %, causing a reduction in the Northern hemispheric carbon sink of 0.4 Pg C yr−1. During the 21st century, ozone-induced reductions in GPP and carbon storage is projected to decline through a combination of air pollution control methods that reduce tropospheric O3 and the indirect effects of rising atmospheric CO2, which reduces stomatal uptake of ozone concurrent with increases of leaf-level water-use efficiency. However, in hotspot regions such as East Asia, the model simulations suggest a sustained decrease of GPP by more than 8 % during the 21st century. Regionally, ozone exposure reduces carbon storage at the end of the 21st century by up to 15 % in parts of Europe, the US and East Asia. These estimates are lower compared to previous studies, which partially results from the explicit representation of non-stomatal ozone destruction, which considerably reduces simulated ozone uptake by leaves and incurred injury. Our simulations suggest that ozone damage largely offsets the growth stimulating effect induced by nitrogen deposition in the Northern hemisphere until the 2050s. Thus, accounting for the stimulating effects of nitrogen deposition but omitting the detrimental effect of O3 might lead to an over estimation of carbon uptake and storage.

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Thermal growing season and timing of biospheric carbon uptake across the Northern Hemisphere

Global Biogeochemical Cycles ◽

10.1029/2012gb004312 ◽

2012 ◽

Vol 26 (4) ◽

pp. n/a-n/a ◽

Cited By ~ 41

Author(s):

J. Barichivich ◽

K. R. Briffa ◽

T. J. Osborn ◽

T. M. Melvin ◽

J. Caesar

Keyword(s):

Northern Hemisphere ◽

Growing Season ◽

Carbon Uptake

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Reduced carbon uptake during the 2010 Northern Hemisphere summer from GOSAT

Geophysical Research Letters ◽

10.1002/grl.50402 ◽

2013 ◽

Vol 40 (10) ◽

pp. 2378-2383 ◽

Cited By ~ 53

Author(s):

S. Guerlet ◽

S. Basu ◽

A. Butz ◽

M. Krol ◽

P. Hahne ◽

...

Keyword(s):

Northern Hemisphere ◽

Carbon Uptake

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Continued increase in atmospheric CO<sub>2</sub> seasonal amplitude in the 21st century projected by the CMIP5 Earth system models

Earth System Dynamics ◽

10.5194/esd-5-423-2014 ◽

2014 ◽

Vol 5 (2) ◽

pp. 423-439 ◽

Cited By ~ 21

Author(s):

F. Zhao ◽

N. Zeng

Keyword(s):

Northern Hemisphere ◽

21St Century ◽

Seasonal Cycle ◽

Co2 Concentration ◽

Growing Season ◽

Carbon Uptake ◽

Earth System ◽

System Models ◽

Amplitude Increase ◽

Earth System Models

Abstract. In the Northern Hemisphere, atmospheric CO2 concentration declines in spring and summer, and rises in fall and winter. Ground-based and aircraft-based observation records indicate that the amplitude of this seasonal cycle has increased in the past. Will this trend continue in the future? In this paper, we analyzed simulations for historical (1850–2005) and future (RCP8.5, 2006–2100) periods produced by 10 Earth system models participating in the fifth phase of the Coupled Model Intercomparison Project (CMIP5). Our results present a model consensus that the increase of CO2 seasonal amplitude continues throughout the 21st century. Multi-model ensemble relative amplitude of detrended global mean CO2 seasonal cycle increases by 62 ± 19% in 2081–2090, compared to 1961–1970. This amplitude increase corresponds to a 68 ± 25% increase in net biosphere production (NBP). The results show that the increase of NBP amplitude mainly comes from enhanced ecosystem uptake during Northern Hemisphere growing season under future CO2 and temperature conditions. Separate analyses on net primary production (NPP) and respiration reveal that enhanced ecosystem carbon uptake contributes about 75% of the amplitude increase. Stimulated by higher CO2 concentration and high-latitude warming, enhanced NPP likely outcompetes increased respiration at higher temperature, resulting in a higher net uptake during the northern growing season. The zonal distribution and spatial pattern of NBP change suggest that regions north of 45° N dominate the amplitude increase. Models that simulate a stronger carbon uptake also tend to show a larger increase of NBP seasonal amplitude, and the cross-model correlation is significant (R=0.73, p< 0.05).

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Alpha-Effect, Current and Kinetic Helicities for Magnetically Driven Turbulence, and Solar Dynamo

International Astronomical Union Colloquium ◽

10.1017/s0252921100064885 ◽

2000 ◽

Vol 179 ◽

pp. 387-388

Author(s):

Gaetano Belvedere ◽

V. V. Pipin ◽

G. Rüdiger

Keyword(s):

Southern Hemisphere ◽

Northern Hemisphere ◽

Convection Zone ◽

Solar Surface ◽

Momentum Transport ◽

Angular Momentum Transport ◽

Magnetic Buoyancy ◽

Alpha Effect ◽

Current Helicity

Extended AbstractRecent numerical simulations lead to the result that turbulence is much more magnetically driven than believed. In particular the role ofmagnetic buoyancyappears quite important for the generation ofα-effect and angular momentum transport (Brandenburg & Schmitt 1998). We present results obtained for a turbulence field driven by a (given) Lorentz force in a non-stratified but rotating convection zone. The main result confirms the numerical findings of Brandenburg & Schmitt that in the northern hemisphere theα-effect and the kinetic helicityℋkin= 〈u′ · rotu′〉 are positive (and negative in the northern hemisphere), this being just opposite to what occurs for the current helicityℋcurr= 〈j′ ·B′〉, which is negative in the northern hemisphere (and positive in the southern hemisphere). There has been an increasing number of papers presenting observations of current helicity at the solar surface, all showing that it isnegativein the northern hemisphere and positive in the southern hemisphere (see Rüdigeret al. 2000, also for a review).

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The Hemispheric Sign Rule of Current Helicity during the Rising Phase of Cycle 23

International Astronomical Union Colloquium ◽

10.1017/s0252921100064721 ◽

2000 ◽

Vol 179 ◽

pp. 303-306

Author(s):

S. D. Bao ◽

G. X. Ai ◽

H. Q. Zhang

Keyword(s):

Solar Cycle ◽

Southern Hemisphere ◽

Northern Hemisphere ◽

Active Regions ◽

Hemispheric Preference ◽

Current Helicity

AbstractWe compute the signs of two different current helicity parameters (i.e., αbestandHc) for 87 active regions during the rise of cycle 23. The results indicate that 59% of the active regions in the northern hemisphere have negative αbestand 65% in the southern hemisphere have positive. This is consistent with that of the cycle 22. However, the helicity parameterHcshows a weaker opposite hemispheric preference in the new solar cycle. Possible reasons are discussed.

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Status of “AGK4” Project

International Astronomical Union Colloquium ◽

10.1017/s0252921100074558 ◽

1978 ◽

Vol 48 ◽

pp. 527-533

Author(s):

Chr. de Vegt

Keyword(s):

Northern Hemisphere ◽

Proper Motion ◽

The Mean ◽

Spectral Bandpass

The present accuracy limit for the majority of fainter stars on the northern hemisphere is set by the AGK2/3-catalogue, recently completely finished, but it should be noted that its epoch is much earlier (1960). Furtheron the AGK3-catalogue is a direct repetition of the AGK2, the plates have been taken with the same astrograph in a broad blue spectral bandpass and measured visually with the same equipment, therefore virtually an instrumental standard of 1930 is realized again. Figure 1 shows the mean errors of the AGK2/3 catalogue positions as a function of magnitude. The best accuracy for the AGK2/3 data is obtained for the stars of about ninth magnitude: 017 (AGK2) and 020 (AGK3) but decreases for the faint stars with mpg11 to 019 (AGK2) and Pg 027 (AGK3). Here the AGK3 data are even less accurate. With increasing distance to the catalogue epochs, the accuracy of positions decreases due to the proper motion errors. In the upper part of figure 2 the dependence of the AGK2/3 catalogue accuracy on time is shown for the faint stars separately and an averaged value.

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