The Nexus Approach to Managing Water, Soil and Waste under Changing Climate and Growing Demands on Natural Resources - Governing the Nexus: Water, Soil and Waste Resources Considering Global Change - page 37

Chapter 3
The Nexus Approach to Managing Water,
Soil and Waste under Changing Climate
and Growing Demands on Natural
Resources

Rattan Lal

1 Introduction

The human population has increased more than a thousand times from 2 - 20 million
at the dawn of settled agriculture about 10 12 millennia ago to 7.2 billion in 2013.

It is projected to reach 9.6 billion by 2050 and

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11 billion by 2100 (UN 2012 ).
The unprecedented growth, not only in the number, but also in the af

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uent lifestyle,

is impacting Earth is biogeochemical processes, and some even beyond the plane-

tary boundaries (Rockstr

'

m et al. 2009 ). The agroecosystems and related activities
are already covering 38 % of the Earth

ö

35 % of the
global greenhouse gases (GHGs) and using 71 % of the global freshwater with-
drawal (Foley et al. 2011 ). With the focus on agricultural intensi

' s terrestrial surface, emitting 30

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cation since the
1960s, the irrigated land area has increased by a factor of two, fertilizer use by ve

and nitrogen use by eight. The present water use by agriculture of 3,100 km 3 /year is
expected to increase to 4,500 km 3 /year by 2030 (McKinsey and Co. 2009 ). Con-
sequently, global food production must be increased by 50 % by 2030 and 100 %
by 2050 (OECD 2010 ). Above all, 24 % of the terrestrial ecosystems are degraded
and more are prone to anthropogenic perturbations (Bai et al. 2008 ), and land, water
and air quality are at risk (Tilman et al. 2011 ). Estimates of food-insecure popu-
lation in 2012 vary from 868 million (FAO 2012 ) to 1.33 billion (Small Planet
Institute 2013 ). Despite large appropriation of global net primary productivity
(NPP) by humans, more than one out of seven persons are food-insecure (Small
Planet Institute 2013 ), two out of seven are prone to de ciency of iron and other

micronutrients (WHO 2013 ), and almost all of the food-insecure people live in
developing countries where natural resources are already under great stress (FAO
2012 ). Faced with these challenges, and the concern that the current increase in crop