| 1. |
- Nordell, Bo
(författare)
-
Thermal pollution causes global warming
- 2003
-
Ingår i: Global and Planetary Change. - 0921-8181 .- 1872-6364. ; 38:3-4, s. 305-312
-
Tidskriftsartikel (refereegranskat)abstract
- Over longer time-scales there is no net heat inflow to Earth since incoming solar energy is re-emitted at exactly the same rate. To maintain Earth's thermal equilibrium, however, there must be a net outflow equal to the geothermal heat flow. Performed calculations show that the net heat outflow in 1880 was equal to the geothermal heat flow, which is the only natural net heat source on Earth. Since then, heat dissipation from the global use of nonrenewable energy sources has resulted in additional net heating. In, e.g. Sweden, which is a sparsely populated country, this net heating is about three times greater than the geothermal heat flow. Such thermal pollution contributes to global warming until the global temperature has reached a level where this heat is also emitted to space. Heat dissipation from the global use of fossil fuels and nuclear power is the main source of thermal pollution. Here, it was found that one third of current thermal pollution is emitted to space and that a further global temperature increase of 1.8 °C is required until Earth is again in thermal equilibrium.
|
|
| 2. |
- Jönsson, Anna Maria, et al.
(författare)
-
Climate change and the effect of temperature backlashes causing frost damage in Picea abies
- 2004
-
Ingår i: Global and Planetary Change. - : Elsevier BV. - 1872-6364 .- 0921-8181. ; 44:1-4, s. 195-207
-
Tidskriftsartikel (refereegranskat)abstract
- In boreal and nemoboreal forests, tree frost hardiness is modified in reaction to cues from day length and temperature. The dehardening processes in Norway spruce, Picea abies, could be estimated to start when the daily mean temperature is above 5 degreesC for 5 days. Bud burst will occur approximately after 120-170 degree-days above 5 degreesC. dependent on genetic differences among provenances. A reduced cold hardiness level during autumn and spring and an advanced onset of bud burst are expected impacts of projected future global wart-ning. The aim of this study was to test if this will increase the risk for frost damage caused by temperature backlashes. This was tested for Sweden by comparing output from the Hadley Centre regional climate model, HadRM3H, for the period 1961-1990 with future IPCC scenario SRES A2 and B2 for 2070-2099. Different indices for calculating the susceptibility to frost damage were used to assess changes in frost damage risk. The indices were based on: (1) the start of dehardening; (2) the severity of the temperature backlash: (3) the timing of bud burst: and (4) the cold hardiness level. The start of dehardening and bud burst were calculated to occur earlier all over the country. which is in line with the overall warming in both climate change scenarios. The frequency of temperature backlashes that may cause frost damage was calculated to increase in the southern part, an effect that became gradually less pronounced towards the north. The different timing of the onset of dehardening mainly caused this systematic latitudinal pattern. In the south, it occurs early in the year when the seasonal temperature progression is slow and large temperature variations occur. In the north, dehardening will occur closer to the spring equinox when the temperature progression is faster. (C) 2004 Elsevier B.V. All rights reserved.
|
|
