Đang chuẩn bị liên kết để tải về tài liệu:
Climate Change and Managed Ecosystems - Chapter 4

Mặc dù biến động khí hậu đã xảy ra thường xuyên hơn 420.000 năm qua, tỷ lệ gia tăng nhiệt độ trong vòng 100 năm qua chưa từng có trong cả hai cường độ và nguyên nhân. Tương tự, tỷ lệ gia tăng khí nhà kính trong khí quyển (GHG) nồng độ trong thế kỷ 20 không xuất hiện trong các bản ghi Paleo, và duyên hệ liên kết với những thay đổi gần đây nhiệt độ toàn cầu. Đáng chú ý, con người phát triển công nghiệp rõ ràng là liên kết cho những thay đổi trong nồng độ khí nhà kính. Hơn nửa trước. | Part II Managed Ecosystems State of Knowledge 2006 by Taylor Francis Group LLC 4 Anthropogenic Changes and the Global Carbon Cycle J.S. Bhatti M.J. Apps and R. Lal CONTENTS 4.1 Introduction.71 4.2 Global Carbon Cycle.72 4.2.1 Carbon Pools.72 4.2.2 Carbon Exchange.73 4.3 Land Use and Land-Use Change.76 4.4 CO2 Fertilization.79 4.5 NOX Fertilization and Ozone.80 4.6 Land Degradation.82 4.7 Soil Erosion. 84 4.8 Wetland Drainage. 85 4.9 Conclusion. 86 References. 88 4.1 INTRODUCTION Although climatic fluctuations have occurred often over the past 420 000 years the rates of increase in temperature in the last 100 years are unprecedented in both magnitude and cause. Similarly the rates of increase in atmospheric greenhouse gas GHG concentrations over the 20th century do not appear in the paleo record and are causally linked with the recent changes in global temperature. Significantly human industrial development is clearly linked to for the changes in GHG concentrations. Over much of the preceding half million years the fluctuations of atmospheric GHGs and global average temperature remained in a relatively narrow correlated band Chapter 2 implying a natural balance in the exchange of GHGs between the atmosphere and planetary surface.1 The 19th century however witnessed the start of a dramatic change in this balance which to date has already recorded a 32 increase in CO2 relative to the average of the past 420 000 years a change whose rate is still accelerating.2 These changes have been driven by human perturbations to the global carbon C cycle changes that 71 2006 by Taylor Francis Group LLC 72 Climate Change and Managed Ecosystems have been both direct introducing new C to the active cycle through fossil fuel use and land-use change LUC and indirect affecting the biospheric portion of the active C cycle through environmental stresses and perturbations to other global biogeochemical cycles. The observed response of the global climate system to this change during the .